Designing secure RFID protocols for EPC Gen2V2 Standard is a challenging work. To solve the problems, recently many mutual authentication protocols have been proposed. However, many of them do not maintain synchrony of the records every interrogation. In this paper, we analyze the recently proposed RFID authentication protocols and show that there is the weakness. And we propose a new mutual authentication protocol for EPC Gen2V2 Standard to maintain synchrony. Furthermore, we analyze our protocol from security and privacy, and it shows that the proposed protocol is secure and effective.