diff --git a/attestation/tee/demo/qca_demo/qcatools/qcautils.go b/attestation/tee/demo/qca_demo/qcatools/qcautils.go
index 51a23ff7ff7ee3d649a3077cf1cc6beb32cea376..0305ad3de194c032b3607baa9164e70645eb33f9 100644
--- a/attestation/tee/demo/qca_demo/qcatools/qcautils.go
+++ b/attestation/tee/demo/qca_demo/qcatools/qcautils.go
@@ -466,7 +466,7 @@ func RecvData(conn net.Conn, outData interface{}) error {
 			return fmt.Errorf("read data failed, %v", err)
 		}
 
-		buf = append(buf, partbuf...)
+		buf = append(buf, partbuf[:n]...)
 		
 		if len(buf) == int(readlen) {
 			break