diff --git a/examples/stream_aggregate_example.go b/examples/stream_aggregate_example.go
index fd5894d..f91d90f 100644
--- a/examples/stream_aggregate_example.go
+++ b/examples/stream_aggregate_example.go
@@ -36,9 +36,11 @@ func main() {
 		docs = append(docs, doc)
 	}
 
-	if err := store.InsertMany(collection, docs); err != nil {
-		log.Printf("Error inserting documents: %v", err)
-		return
+	for _, doc := range docs {
+		if err := store.Insert(collection, doc); err != nil {
+			log.Printf("Error inserting document: %v", err)
+			return
+		}
 	}
 
 	// 定义聚合管道
diff --git a/internal/engine/crud_handler.go b/internal/engine/crud_handler.go
index 6141c1a..24b16e6 100644
--- a/internal/engine/crud_handler.go
+++ b/internal/engine/crud_handler.go
@@ -54,8 +54,8 @@ func (h *CRUDHandler) Insert(ctx context.Context, collection string, docs []map[
 }
 
 // Update 更新文档
-func (h *CRUDHandler) Update(ctx context.Context, collection string, filter types.Filter, update types.Update) (*types.UpdateResult, error) {
-	matched, modified, _, err := h.store.Update(collection, filter, update, false, nil)
+func (h *CRUDHandler) Update(ctx context.Context, collection string, filter types.Filter, update types.Update, upsert bool) (*types.UpdateResult, error) {
+	matched, modified, _, err := h.store.Update(collection, filter, update, upsert, nil)
 	if err != nil {
 		return nil, err
 	}
diff --git a/internal/engine/memory_store.go b/internal/engine/memory_store.go
index 847d3db..7907dca 100644
--- a/internal/engine/memory_store.go
+++ b/internal/engine/memory_store.go
@@ -388,6 +388,12 @@ func (ms *MemoryStore) Update(collection string, filter types.Filter, update typ
 	if matched == 0 && upsert {
 		// 创建新文档
 		newID := generateID()
+		// 优先使用 filter 中的 _id
+		if idVal, ok := filter["_id"]; ok {
+			if idStr, ok := idVal.(string); ok && idStr != "" {
+				newID = idStr
+			}
+		}
 		newDoc := make(map[string]interface{})
 
 		// 应用更新（$setOnInsert 会生效）
diff --git a/internal/protocol/http/server.go b/internal/protocol/http/server.go
index 2447d63..fa7f4e8 100644
--- a/internal/protocol/http/server.go
+++ b/internal/protocol/http/server.go
@@ -271,7 +271,7 @@ func (h *RequestHandler) HandleUpdate(w http.ResponseWriter, r *http.Request, db
 	upserted := make([]types.UpsertID, 0)
 
 	for _, op := range req.Updates {
-		result, err := h.crud.Update(context.Background(), fullCollection, op.Q, op.U)
+		result, err := h.crud.Update(context.Background(), fullCollection, op.Q, op.U, op.Upsert)
 		if err != nil {
 			http.Error(w, err.Error(), http.StatusInternalServerError)
 			return