diff --git a/internal/db/mongodb_impl.go b/internal/db/mongodb_impl.go
index 5c853f6..27ac0c7 100644
--- a/internal/db/mongodb_impl.go
+++ b/internal/db/mongodb_impl.go
@@ -251,6 +251,11 @@ func (m *MongoDB) getURI(config connection.ConnectionConfig) string {
 		params.Set("authMechanism", authMechanism)
 	}
 
+	// 单机模式且未指定副本集名称时，启用 directConnection 避免驱动自动跟随副本集成员发现
+	if strings.TrimSpace(config.Topology) != "replica" && strings.TrimSpace(config.ReplicaSet) == "" && !config.MongoSRV {
+		params.Set("directConnection", "true")
+	}
+
 	if encoded := params.Encode(); encoded != "" {
 		uri += "?" + encoded
 	}
diff --git a/internal/db/mongodb_impl_v1.go b/internal/db/mongodb_impl_v1.go
index 26e110a..e3aa5b4 100644
--- a/internal/db/mongodb_impl_v1.go
+++ b/internal/db/mongodb_impl_v1.go
@@ -252,6 +252,11 @@ func (m *MongoDBV1) getURI(config connection.ConnectionConfig) string {
 		params.Set("authMechanism", authMechanism)
 	}
 
+	// 单机模式且未指定副本集名称时，启用 directConnection 避免驱动自动跟随副本集成员发现
+	if strings.TrimSpace(config.Topology) != "replica" && strings.TrimSpace(config.ReplicaSet) == "" && !config.MongoSRV {
+		params.Set("directConnection", "true")
+	}
+
 	if encoded := params.Encode(); encoded != "" {
 		uri += "?" + encoded
 	}