diff --git a/core/txdb/txdb.go b/core/txdb/txdb.go
index 02686e4..19bf5a1 100644
--- a/core/txdb/txdb.go
+++ b/core/txdb/txdb.go
@@ -1,6 +1,8 @@
 package txdb
 
 import (
+	"sync"
+
 	"github.com/sirupsen/logrus"
 
 	. "github.com/yu-org/yu/common"
@@ -18,13 +20,58 @@ const (
 type TxDB struct {
 	nodeType int
 
-	txnKV     kv.KV
-	receiptKV kv.KV
+	txnKV     *txnkvdb
+	receiptKV *receipttxnkvdb
 
 	enableUseSql bool
 	db           sql.SqlDB
 }
 
+type txnkvdb struct {
+	sync.RWMutex
+	txnKV kv.KV
+}
+
+func (t *txnkvdb) GetTxn(txnHash Hash) (*SignedTxn, error) {
+	t.RLock()
+	defer t.RUnlock()
+	byt, err := t.txnKV.Get(txnHash.Bytes())
+	if err != nil {
+		return nil, err
+	}
+	if byt == nil {
+		return nil, nil
+	}
+	return DecodeSignedTxn(byt)
+}
+
+func (t *txnkvdb) ExistTxn(txnHash Hash) bool {
+	t.RLock()
+	defer t.RUnlock()
+	return t.txnKV.Exist(txnHash.Bytes())
+}
+
+func (t *txnkvdb) SetTxns(txns []*SignedTxn) error {
+	t.Lock()
+	defer t.Unlock()
+	kvtx, err := t.txnKV.NewKvTxn()
+	if err != nil {
+		return err
+	}
+	for _, txn := range txns {
+		txbyt, err := txn.Encode()
+		if err != nil {
+			logrus.Errorf("TxDB.SetTxns set tx(%s) failed: %v", txn.TxnHash.String(), err)
+			return err
+		}
+		err = kvtx.Set(txn.TxnHash.Bytes(), txbyt)
+		if err != nil {
+			return err
+		}
+	}
+	return kvtx.Commit()
+}
+
 type TxnDBSchema struct {
 	Type  string `gorm:"type:varchar(10)"`
 	Key   string `gorm:"primaryKey;type:text"`
@@ -38,8 +85,8 @@ func (TxnDBSchema) TableName() string {
 func NewTxDB(nodeTyp int, kvdb kv.Kvdb, kvdbConf *config.KVconf) (ItxDB, error) {
 	txdb := &TxDB{
 		nodeType:  nodeTyp,
-		txnKV:     kvdb.New(Txns),
-		receiptKV: kvdb.New(Results),
+		txnKV:     &txnkvdb{txnKV: kvdb.New(Txns)},
+		receiptKV: &receipttxnkvdb{receiptKV: kvdb.New(Results)},
 	}
 	if kvdbConf != nil && kvdbConf.UseSQlDbConf {
 		db, err := sql.NewSqlDB(&kvdbConf.SQLDbConf)
@@ -67,14 +114,7 @@ func (bb *TxDB) GetTxn(txnHash Hash) (*SignedTxn, error) {
 			return DecodeSignedTxn([]byte(records[0].Value))
 		}
 	}
-	byt, err := bb.txnKV.Get(txnHash.Bytes())
-	if err != nil {
-		return nil, err
-	}
-	if byt == nil {
-		return nil, nil
-	}
-	return DecodeSignedTxn(byt)
+	return bb.txnKV.GetTxn(txnHash)
 }
 
 func (bb *TxDB) GetTxns(txnHashes []Hash) ([]*SignedTxn, error) {
@@ -103,7 +143,7 @@ func (bb *TxDB) ExistTxn(txnHash Hash) bool {
 			return true
 		}
 	}
-	return bb.txnKV.Exist(txnHash.Bytes())
+	return bb.txnKV.ExistTxn(txnHash)
 }
 
 func (bb *TxDB) SetTxns(txns []*SignedTxn) error {
@@ -124,22 +164,7 @@ func (bb *TxDB) SetTxns(txns []*SignedTxn) error {
 		}
 		return nil
 	}
-	kvtx, err := bb.txnKV.NewKvTxn()
-	if err != nil {
-		return err
-	}
-	for _, txn := range txns {
-		txbyt, err := txn.Encode()
-		if err != nil {
-			logrus.Errorf("TxDB.SetTxns set tx(%s) failed: %v", txn.TxnHash.String(), err)
-			return err
-		}
-		err = kvtx.Set(txn.TxnHash.Bytes(), txbyt)
-		if err != nil {
-			return err
-		}
-	}
-	return kvtx.Commit()
+	return bb.txnKV.SetTxns(txns)
 }
 
 func (bb *TxDB) SetReceipts(receipts map[Hash]*Receipt) error {
@@ -151,22 +176,7 @@ func (bb *TxDB) SetReceipts(receipts map[Hash]*Receipt) error {
 		}
 		return nil
 	}
-	kvtx, err := bb.receiptKV.NewKvTxn()
-	if err != nil {
-		return err
-	}
-	for txHash, receipt := range receipts {
-		byt, err := receipt.Encode()
-		if err != nil {
-			return err
-		}
-		err = kvtx.Set(txHash.Bytes(), byt)
-		if err != nil {
-			return err
-		}
-	}
-
-	return kvtx.Commit()
+	return bb.receiptKV.SetReceipts(receipts)
 }
 
 func (bb *TxDB) SetReceipt(txHash Hash, receipt *Receipt) error {
@@ -180,11 +190,7 @@ func (bb *TxDB) SetReceipt(txHash Hash, receipt *Receipt) error {
 		}
 		return nil
 	}
-	byt, err := receipt.Encode()
-	if err != nil {
-		return err
-	}
-	return bb.receiptKV.Set(txHash.Bytes(), byt)
+	return bb.receiptKV.SetReceipt(txHash, receipt)
 }
 
 func (bb *TxDB) GetReceipt(txHash Hash) (*Receipt, error) {
@@ -199,7 +205,18 @@ func (bb *TxDB) GetReceipt(txHash Hash) (*Receipt, error) {
 			}
 		}
 	}
-	byt, err := bb.receiptKV.Get(txHash.Bytes())
+	return bb.receiptKV.GetReceipt(txHash)
+}
+
+type receipttxnkvdb struct {
+	sync.RWMutex
+	receiptKV kv.KV
+}
+
+func (r *receipttxnkvdb) GetReceipt(txHash Hash) (*Receipt, error) {
+	r.RLock()
+	defer r.RUnlock()
+	byt, err := r.receiptKV.Get(txHash.Bytes())
 	if err != nil {
 		logrus.Errorf("TxDB.GetReceipt(%s), failed: %s, error: %v", txHash.String(), string(byt), err)
 		return nil, err
@@ -214,3 +231,33 @@ func (bb *TxDB) GetReceipt(txHash Hash) (*Receipt, error) {
 	}
 	return receipt, err
 }
+
+func (r *receipttxnkvdb) SetReceipt(txHash Hash, receipt *Receipt) error {
+	r.Lock()
+	defer r.Unlock()
+	byt, err := receipt.Encode()
+	if err != nil {
+		return err
+	}
+	return r.receiptKV.Set(txHash.Bytes(), byt)
+}
+
+func (r *receipttxnkvdb) SetReceipts(receipts map[Hash]*Receipt) error {
+	r.Lock()
+	defer r.Unlock()
+	kvtx, err := r.receiptKV.NewKvTxn()
+	if err != nil {
+		return err
+	}
+	for txHash, receipt := range receipts {
+		byt, err := receipt.Encode()
+		if err != nil {
+			return err
+		}
+		err = kvtx.Set(txHash.Bytes(), byt)
+		if err != nil {
+			return err
+		}
+	}
+	return kvtx.Commit()
+}