diff --git a/frontend/src/components/ConnectionModal.tsx b/frontend/src/components/ConnectionModal.tsx
index 037d76b..c1f17a8 100644
--- a/frontend/src/components/ConnectionModal.tsx
+++ b/frontend/src/components/ConnectionModal.tsx
@@ -2101,7 +2101,7 @@ const ConnectionModal: React.FC<{
                               <Form.Item
                                   name="user"
                                   label="用户名"
-                                  rules={[createUriAwareRequiredRule('请输入用户名')]}
+                                  rules={dbType === 'mongodb' ? [] : [createUriAwareRequiredRule('请输入用户名')]}
                                   style={{ marginBottom: 0 }}
                               >
                                   <Input />
@@ -2115,6 +2115,7 @@ const ConnectionModal: React.FC<{
                                           allowClear
                                           placeholder="自动协商"
                                           options={[
+                                              { value: 'NONE', label: '无认证 (None)' },
                                               { value: 'SCRAM-SHA-1', label: 'SCRAM-SHA-1' },
                                               { value: 'SCRAM-SHA-256', label: 'SCRAM-SHA-256' },
                                               { value: 'MONGODB-AWS', label: 'MONGODB-AWS' },
diff --git a/internal/db/mongodb_impl.go b/internal/db/mongodb_impl.go
index 2e5131c..ec73c46 100644
--- a/internal/db/mongodb_impl.go
+++ b/internal/db/mongodb_impl.go
@@ -215,7 +215,9 @@ func (m *MongoDB) getURI(config connection.ConnectionConfig) string {
 	hostText := strings.Join(seeds, ",")
 	uri := fmt.Sprintf("%s://%s", scheme, hostText)
 
-	if config.User != "" {
+	noAuth := strings.EqualFold(strings.TrimSpace(config.MongoAuthMechanism), "NONE")
+
+	if config.User != "" && !noAuth {
 		var userinfo *url.Userinfo
 		if config.Password != "" {
 			userinfo = url.UserPassword(config.User, config.Password)
@@ -236,11 +238,14 @@ func (m *MongoDB) getURI(config connection.ConnectionConfig) string {
 	params.Set("connectTimeoutMS", strconv.Itoa(timeout*1000))
 	params.Set("serverSelectionTimeoutMS", strconv.Itoa(timeout*1000))
 
-	authSource := strings.TrimSpace(config.AuthSource)
-	if authSource == "" {
-		authSource = "admin"
+	// 仅在有用户名且非 NONE 认证时设置 authSource
+	if config.User != "" && !noAuth {
+		authSource := strings.TrimSpace(config.AuthSource)
+		if authSource == "" {
+			authSource = "admin"
+		}
+		params.Set("authSource", authSource)
 	}
-	params.Set("authSource", authSource)
 
 	if replicaSet := strings.TrimSpace(config.ReplicaSet); replicaSet != "" {
 		params.Set("replicaSet", replicaSet)
@@ -248,7 +253,8 @@ func (m *MongoDB) getURI(config connection.ConnectionConfig) string {
 	if readPreference := strings.TrimSpace(config.ReadPreference); readPreference != "" {
 		params.Set("readPreference", readPreference)
 	}
-	if authMechanism := strings.TrimSpace(config.MongoAuthMechanism); authMechanism != "" {
+	// NONE 表示无认证，不设置 authMechanism
+	if authMechanism := strings.TrimSpace(config.MongoAuthMechanism); authMechanism != "" && !noAuth {
 		params.Set("authMechanism", authMechanism)
 	}
 
diff --git a/internal/db/mongodb_impl_v1.go b/internal/db/mongodb_impl_v1.go
index c746431..17bf146 100644
--- a/internal/db/mongodb_impl_v1.go
+++ b/internal/db/mongodb_impl_v1.go
@@ -216,7 +216,9 @@ func (m *MongoDBV1) getURI(config connection.ConnectionConfig) string {
 	hostText := strings.Join(seeds, ",")
 	uri := fmt.Sprintf("%s://%s", scheme, hostText)
 
-	if config.User != "" {
+	noAuth := strings.EqualFold(strings.TrimSpace(config.MongoAuthMechanism), "NONE")
+
+	if config.User != "" && !noAuth {
 		var userinfo *url.Userinfo
 		if config.Password != "" {
 			userinfo = url.UserPassword(config.User, config.Password)
@@ -237,11 +239,14 @@ func (m *MongoDBV1) getURI(config connection.ConnectionConfig) string {
 	params.Set("connectTimeoutMS", strconv.Itoa(timeout*1000))
 	params.Set("serverSelectionTimeoutMS", strconv.Itoa(timeout*1000))
 
-	authSource := strings.TrimSpace(config.AuthSource)
-	if authSource == "" {
-		authSource = "admin"
+	// 仅在有用户名且非 NONE 认证时设置 authSource
+	if config.User != "" && !noAuth {
+		authSource := strings.TrimSpace(config.AuthSource)
+		if authSource == "" {
+			authSource = "admin"
+		}
+		params.Set("authSource", authSource)
 	}
-	params.Set("authSource", authSource)
 
 	if replicaSet := strings.TrimSpace(config.ReplicaSet); replicaSet != "" {
 		params.Set("replicaSet", replicaSet)
@@ -249,7 +254,8 @@ func (m *MongoDBV1) getURI(config connection.ConnectionConfig) string {
 	if readPreference := strings.TrimSpace(config.ReadPreference); readPreference != "" {
 		params.Set("readPreference", readPreference)
 	}
-	if authMechanism := strings.TrimSpace(config.MongoAuthMechanism); authMechanism != "" {
+	// NONE 表示无认证，不设置 authMechanism
+	if authMechanism := strings.TrimSpace(config.MongoAuthMechanism); authMechanism != "" && !noAuth {
 		params.Set("authMechanism", authMechanism)
 	}