diff --git a/internal/balancer/balancer.go b/internal/balancer/balancer.go
index 8b3d508..12706df 100644
--- a/internal/balancer/balancer.go
+++ b/internal/balancer/balancer.go
@@ -1,25 +1,14 @@
 package balancer
 
 import (
-	"crypto/md5"
-	"encoding/binary"
 	"fmt"
-	"math/rand"
-	"sort"
-	"sync"
-	"sync/atomic"
 
 	"github.com/DullJZ/s3-balance/internal/bucket"
 	"github.com/DullJZ/s3-balance/internal/config"
 )
 
-// Strategy 负载均衡策略接口
-type Strategy interface {
-	SelectBucket(buckets []*bucket.BucketInfo, key string, size int64) (*bucket.BucketInfo, error)
-	Name() string
-}
-
 // Balancer 负载均衡器
+// 负责根据配置的策略选择合适的存储桶
 type Balancer struct {
 	manager  *bucket.Manager
 	strategy Strategy
@@ -30,6 +19,7 @@ type Balancer struct {
 func NewBalancer(manager *bucket.Manager, cfg *config.BalancerConfig) (*Balancer, error) {
 	var strategy Strategy
 	
+	// 根据配置创建对应的策略实例
 	switch cfg.Strategy {
 	case "round-robin":
 		strategy = NewRoundRobinStrategy()
@@ -51,6 +41,7 @@ func NewBalancer(manager *bucket.Manager, cfg *config.BalancerConfig) (*Balancer
 }
 
 // SelectBucket 选择一个存储桶
+// 首先过滤出有足够空间的存储桶，然后使用策略选择
 func (b *Balancer) SelectBucket(key string, size int64) (*bucket.BucketInfo, error) {
 	// 获取所有可用的存储桶
 	buckets := b.manager.GetAvailableBuckets()
@@ -84,181 +75,60 @@ func (b *Balancer) GetStrategy() string {
 	return b.strategy.Name()
 }
 
-// RoundRobinStrategy 轮询策略
-type RoundRobinStrategy struct {
-	counter uint64
-}
-
-// NewRoundRobinStrategy 创建轮询策略
-func NewRoundRobinStrategy() *RoundRobinStrategy {
-	return &RoundRobinStrategy{}
-}
-
-// SelectBucket 选择存储桶（轮询）
-func (s *RoundRobinStrategy) SelectBucket(buckets []*bucket.BucketInfo, key string, size int64) (*bucket.BucketInfo, error) {
-	if len(buckets) == 0 {
-		return nil, fmt.Errorf("no buckets available")
+// SetStrategy 动态切换策略
+// 允许在运行时更改负载均衡策略
+func (b *Balancer) SetStrategy(strategyName string) error {
+	var strategy Strategy
+	
+	switch strategyName {
+	case "round-robin":
+		strategy = NewRoundRobinStrategy()
+	case "least-space":
+		strategy = NewLeastSpaceStrategy()
+	case "weighted":
+		strategy = NewWeightedStrategy()
+	case "consistent-hash":
+		strategy = NewConsistentHashStrategy()
+	default:
+		return fmt.Errorf("unknown balancer strategy: %s", strategyName)
 	}
 	
-	index := atomic.AddUint64(&s.counter, 1) % uint64(len(buckets))
-	return buckets[index], nil
+	b.strategy = strategy
+	return nil
 }
 
-// Name 返回策略名称
-func (s *RoundRobinStrategy) Name() string {
-	return "round-robin"
+// GetAvailableBuckets 获取所有可用的存储桶
+// 方便外部直接查询可用存储桶列表
+func (b *Balancer) GetAvailableBuckets() []*bucket.BucketInfo {
+	return b.manager.GetAvailableBuckets()
 }
 
-// LeastSpaceStrategy 最少使用空间策略
-type LeastSpaceStrategy struct{}
-
-// NewLeastSpaceStrategy 创建最少使用空间策略
-func NewLeastSpaceStrategy() *LeastSpaceStrategy {
-	return &LeastSpaceStrategy{}
-}
-
-// SelectBucket 选择存储桶（选择使用空间最少的）
-func (s *LeastSpaceStrategy) SelectBucket(buckets []*bucket.BucketInfo, key string, size int64) (*bucket.BucketInfo, error) {
-	if len(buckets) == 0 {
-		return nil, fmt.Errorf("no buckets available")
-	}
-
-	// 按可用空间排序（从大到小）
-	sort.Slice(buckets, func(i, j int) bool {
-		return buckets[i].GetAvailableSpace() > buckets[j].GetAvailableSpace()
-	})
-
-	return buckets[0], nil
-}
-
-// Name 返回策略名称
-func (s *LeastSpaceStrategy) Name() string {
-	return "least-space"
-}
-
-// WeightedStrategy 加权策略
-type WeightedStrategy struct {
-	mu sync.RWMutex
-}
-
-// NewWeightedStrategy 创建加权策略
-func NewWeightedStrategy() *WeightedStrategy {
-	return &WeightedStrategy{}
-}
-
-// SelectBucket 选择存储桶（基于权重）
-func (s *WeightedStrategy) SelectBucket(buckets []*bucket.BucketInfo, key string, size int64) (*bucket.BucketInfo, error) {
-	if len(buckets) == 0 {
-		return nil, fmt.Errorf("no buckets available")
-	}
-
-	// 计算总权重
-	totalWeight := 0
-	for _, b := range buckets {
-		totalWeight += b.Config.Weight
-	}
-
-	if totalWeight == 0 {
-		// 如果所有权重都是0，则随机选择
-		return buckets[rand.Intn(len(buckets))], nil
-	}
-
-	// 根据权重随机选择
-	randomWeight := rand.Intn(totalWeight)
-	currentWeight := 0
-
-	for _, b := range buckets {
-		currentWeight += b.Config.Weight
-		if randomWeight < currentWeight {
-			return b, nil
+// GetBucketStats 获取存储桶统计信息
+// 返回每个存储桶的使用情况
+func (b *Balancer) GetBucketStats() map[string]BucketStats {
+	stats := make(map[string]BucketStats)
+	buckets := b.manager.GetAllBuckets()
+	
+	for _, bucket := range buckets {
+		stats[bucket.Config.Name] = BucketStats{
+			Name:           bucket.Config.Name,
+			TotalSpace:     bucket.Config.MaxSizeBytes,
+			UsedSpace:      bucket.GetUsedSize(),
+			AvailableSpace: bucket.GetAvailableSpace(),
+			IsAvailable:    bucket.IsAvailable(),
+			Weight:         bucket.Config.Weight,
 		}
 	}
-
-	// 不应该到达这里，但为了安全返回最后一个
-	return buckets[len(buckets)-1], nil
+	
+	return stats
 }
 
-// Name 返回策略名称
-func (s *WeightedStrategy) Name() string {
-	return "weighted"
-}
-
-// ConsistentHashStrategy 一致性哈希策略
-type ConsistentHashStrategy struct {
-	replicas int
-	ring     map[uint32]*bucket.BucketInfo
-	nodes    []uint32
-	mu       sync.RWMutex
-}
-
-// NewConsistentHashStrategy 创建一致性哈希策略
-func NewConsistentHashStrategy() *ConsistentHashStrategy {
-	return &ConsistentHashStrategy{
-		replicas: 100, // 每个节点的虚拟节点数
-		ring:     make(map[uint32]*bucket.BucketInfo),
-	}
-}
-
-// SelectBucket 选择存储桶（基于一致性哈希）
-func (s *ConsistentHashStrategy) SelectBucket(buckets []*bucket.BucketInfo, key string, size int64) (*bucket.BucketInfo, error) {
-	if len(buckets) == 0 {
-		return nil, fmt.Errorf("no buckets available")
-	}
-
-	// 更新哈希环
-	s.updateRing(buckets)
-
-	// 计算key的哈希值
-	hash := s.hash(key)
-
-	// 在环上找到第一个大于等于hash的节点
-	s.mu.RLock()
-	defer s.mu.RUnlock()
-
-	idx := sort.Search(len(s.nodes), func(i int) bool {
-		return s.nodes[i] >= hash
-	})
-
-	// 如果没找到，返回第一个节点（环形结构）
-	if idx == len(s.nodes) {
-		idx = 0
-	}
-
-	return s.ring[s.nodes[idx]], nil
-}
-
-// updateRing 更新哈希环
-func (s *ConsistentHashStrategy) updateRing(buckets []*bucket.BucketInfo) {
-	s.mu.Lock()
-	defer s.mu.Unlock()
-
-	// 清空现有环
-	s.ring = make(map[uint32]*bucket.BucketInfo)
-	s.nodes = nil
-
-	// 为每个存储桶添加虚拟节点
-	for _, b := range buckets {
-		for i := 0; i < s.replicas; i++ {
-			virtualKey := fmt.Sprintf("%s-%d", b.Config.Name, i)
-			hash := s.hash(virtualKey)
-			s.ring[hash] = b
-			s.nodes = append(s.nodes, hash)
-		}
-	}
-
-	// 排序节点
-	sort.Slice(s.nodes, func(i, j int) bool {
-		return s.nodes[i] < s.nodes[j]
-	})
-}
-
-// hash 计算哈希值
-func (s *ConsistentHashStrategy) hash(key string) uint32 {
-	h := md5.Sum([]byte(key))
-	return binary.BigEndian.Uint32(h[:4])
-}
-
-// Name 返回策略名称
-func (s *ConsistentHashStrategy) Name() string {
-	return "consistent-hash"
+// BucketStats 存储桶统计信息
+type BucketStats struct {
+	Name           string `json:"name"`
+	TotalSpace     int64  `json:"total_space"`
+	UsedSpace      int64  `json:"used_space"`
+	AvailableSpace int64  `json:"available_space"`
+	IsAvailable    bool   `json:"is_available"`
+	Weight         int    `json:"weight"`
 }
diff --git a/internal/balancer/consistent_hash.go b/internal/balancer/consistent_hash.go
new file mode 100644
index 0000000..2fd7316
--- /dev/null
+++ b/internal/balancer/consistent_hash.go
@@ -0,0 +1,112 @@
+package balancer
+
+import (
+	"crypto/md5"
+	"encoding/binary"
+	"fmt"
+	"sort"
+	"sync"
+
+	"github.com/DullJZ/s3-balance/internal/bucket"
+)
+
+// ConsistentHashStrategy 一致性哈希策略
+// 使用一致性哈希算法，确保相同的key总是映射到相同的存储桶
+// 当存储桶增加或减少时，能够最小化数据迁移
+type ConsistentHashStrategy struct {
+	replicas int                           // 每个节点的虚拟节点数
+	ring     map[uint32]*bucket.BucketInfo // 哈希环
+	nodes    []uint32                      // 排序的哈希值列表
+	mu       sync.RWMutex                  // 读写锁，保护并发访问
+}
+
+// NewConsistentHashStrategy 创建一致性哈希策略
+func NewConsistentHashStrategy() *ConsistentHashStrategy {
+	return &ConsistentHashStrategy{
+		replicas: 100, // 每个节点的虚拟节点数，越大分布越均匀
+		ring:     make(map[uint32]*bucket.BucketInfo),
+	}
+}
+
+// SelectBucket 选择存储桶（基于一致性哈希）
+// 相同的key总是会映射到相同的存储桶
+func (s *ConsistentHashStrategy) SelectBucket(buckets []*bucket.BucketInfo, key string, size int64) (*bucket.BucketInfo, error) {
+	if len(buckets) == 0 {
+		return nil, fmt.Errorf("no buckets available")
+	}
+
+	// 更新哈希环
+	s.updateRing(buckets)
+
+	// 计算key的哈希值
+	hash := s.hash(key)
+
+	// 在环上找到第一个大于等于hash的节点
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+
+	// 二分查找第一个大于等于hash的节点
+	idx := sort.Search(len(s.nodes), func(i int) bool {
+		return s.nodes[i] >= hash
+	})
+
+	// 如果没找到，返回第一个节点（环形结构）
+	if idx == len(s.nodes) {
+		idx = 0
+	}
+
+	return s.ring[s.nodes[idx]], nil
+}
+
+// updateRing 更新哈希环
+// 为每个存储桶创建多个虚拟节点，使哈希分布更均匀
+func (s *ConsistentHashStrategy) updateRing(buckets []*bucket.BucketInfo) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	// 清空现有环
+	s.ring = make(map[uint32]*bucket.BucketInfo)
+	s.nodes = nil
+
+	// 为每个存储桶添加虚拟节点
+	for _, b := range buckets {
+		for i := 0; i < s.replicas; i++ {
+			// 为每个虚拟节点生成唯一的key
+			virtualKey := fmt.Sprintf("%s-%d", b.Config.Name, i)
+			hash := s.hash(virtualKey)
+			s.ring[hash] = b
+			s.nodes = append(s.nodes, hash)
+		}
+	}
+
+	// 排序节点，便于二分查找
+	sort.Slice(s.nodes, func(i, j int) bool {
+		return s.nodes[i] < s.nodes[j]
+	})
+}
+
+// hash 计算哈希值
+// 使用MD5算法，取前4个字节作为uint32
+func (s *ConsistentHashStrategy) hash(key string) uint32 {
+	h := md5.Sum([]byte(key))
+	return binary.BigEndian.Uint32(h[:4])
+}
+
+// Name 返回策略名称
+func (s *ConsistentHashStrategy) Name() string {
+	return "consistent-hash"
+}
+
+// SetReplicas 设置虚拟节点数
+// 虚拟节点越多，负载分布越均匀，但内存使用也越多
+func (s *ConsistentHashStrategy) SetReplicas(replicas int) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	
+	if replicas > 0 {
+		s.replicas = replicas
+		// 清空现有环，下次选择时会重新构建
+		s.ring = make(map[uint32]*bucket.BucketInfo)
+		s.nodes = nil
+	}
+}
diff --git a/internal/balancer/least_space.go b/internal/balancer/least_space.go
new file mode 100644
index 0000000..31cda34
--- /dev/null
+++ b/internal/balancer/least_space.go
@@ -0,0 +1,39 @@
+package balancer
+
+import (
+	"fmt"
+	"sort"
+
+	"github.com/DullJZ/s3-balance/internal/bucket"
+)
+
+// LeastSpaceStrategy 最少使用空间策略
+// 选择当前使用空间最少（可用空间最多）的存储桶
+type LeastSpaceStrategy struct{}
+
+// NewLeastSpaceStrategy 创建最少使用空间策略
+func NewLeastSpaceStrategy() *LeastSpaceStrategy {
+	return &LeastSpaceStrategy{}
+}
+
+// SelectBucket 选择存储桶（选择使用空间最少的）
+// 优先选择可用空间最大的存储桶，有助于均衡存储使用
+func (s *LeastSpaceStrategy) SelectBucket(buckets []*bucket.BucketInfo, key string, size int64) (*bucket.BucketInfo, error) {
+	if len(buckets) == 0 {
+		return nil, fmt.Errorf("no buckets available")
+	}
+
+	// 按可用空间排序（从大到小）
+	// 使用稳定排序，保证相同可用空间的存储桶保持原有顺序
+	sort.SliceStable(buckets, func(i, j int) bool {
+		return buckets[i].GetAvailableSpace() > buckets[j].GetAvailableSpace()
+	})
+
+	// 返回可用空间最大的存储桶
+	return buckets[0], nil
+}
+
+// Name 返回策略名称
+func (s *LeastSpaceStrategy) Name() string {
+	return "least-space"
+}
diff --git a/internal/balancer/round_robin.go b/internal/balancer/round_robin.go
new file mode 100644
index 0000000..3526db9
--- /dev/null
+++ b/internal/balancer/round_robin.go
@@ -0,0 +1,36 @@
+package balancer
+
+import (
+	"fmt"
+	"sync/atomic"
+
+	"github.com/DullJZ/s3-balance/internal/bucket"
+)
+
+// RoundRobinStrategy 轮询策略
+// 按照固定顺序循环选择存储桶
+type RoundRobinStrategy struct {
+	counter uint64
+}
+
+// NewRoundRobinStrategy 创建轮询策略
+func NewRoundRobinStrategy() *RoundRobinStrategy {
+	return &RoundRobinStrategy{}
+}
+
+// SelectBucket 选择存储桶（轮询）
+// 使用原子操作确保并发安全
+func (s *RoundRobinStrategy) SelectBucket(buckets []*bucket.BucketInfo, key string, size int64) (*bucket.BucketInfo, error) {
+	if len(buckets) == 0 {
+		return nil, fmt.Errorf("no buckets available")
+	}
+	
+	// 原子递增计数器并取模，确保索引在有效范围内
+	index := atomic.AddUint64(&s.counter, 1) % uint64(len(buckets))
+	return buckets[index], nil
+}
+
+// Name 返回策略名称
+func (s *RoundRobinStrategy) Name() string {
+	return "round-robin"
+}
diff --git a/internal/balancer/strategy.go b/internal/balancer/strategy.go
new file mode 100644
index 0000000..ea5e1aa
--- /dev/null
+++ b/internal/balancer/strategy.go
@@ -0,0 +1,15 @@
+package balancer
+
+import "github.com/DullJZ/s3-balance/internal/bucket"
+
+// Strategy 负载均衡策略接口
+type Strategy interface {
+	// SelectBucket 根据策略选择一个存储桶
+	// buckets: 可用的存储桶列表
+	// key: 对象的键
+	// size: 对象的大小
+	SelectBucket(buckets []*bucket.BucketInfo, key string, size int64) (*bucket.BucketInfo, error)
+	
+	// Name 返回策略名称
+	Name() string
+}
diff --git a/internal/balancer/weighted.go b/internal/balancer/weighted.go
new file mode 100644
index 0000000..7b857ce
--- /dev/null
+++ b/internal/balancer/weighted.go
@@ -0,0 +1,63 @@
+package balancer
+
+import (
+	"fmt"
+	"math/rand"
+	"sync"
+
+	"github.com/DullJZ/s3-balance/internal/bucket"
+)
+
+// WeightedStrategy 加权策略
+// 根据存储桶配置的权重进行选择，权重越高被选中的概率越大
+type WeightedStrategy struct {
+	mu sync.RWMutex
+}
+
+// NewWeightedStrategy 创建加权策略
+func NewWeightedStrategy() *WeightedStrategy {
+	return &WeightedStrategy{}
+}
+
+// SelectBucket 选择存储桶（基于权重）
+// 权重越高的存储桶被选中的概率越大
+func (s *WeightedStrategy) SelectBucket(buckets []*bucket.BucketInfo, key string, size int64) (*bucket.BucketInfo, error) {
+	if len(buckets) == 0 {
+		return nil, fmt.Errorf("no buckets available")
+	}
+
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+
+	// 计算总权重
+	totalWeight := 0
+	for _, b := range buckets {
+		totalWeight += b.Config.Weight
+	}
+
+	if totalWeight == 0 {
+		// 如果所有权重都是0，则随机选择
+		return buckets[rand.Intn(len(buckets))], nil
+	}
+
+	// 根据权重随机选择
+	// 生成一个 [0, totalWeight) 范围内的随机数
+	randomWeight := rand.Intn(totalWeight)
+	currentWeight := 0
+
+	// 遍历存储桶，累加权重直到超过随机数
+	for _, b := range buckets {
+		currentWeight += b.Config.Weight
+		if randomWeight < currentWeight {
+			return b, nil
+		}
+	}
+
+	// 不应该到达这里，但为了安全返回最后一个
+	return buckets[len(buckets)-1], nil
+}
+
+// Name 返回策略名称
+func (s *WeightedStrategy) Name() string {
+	return "weighted"
+}