In order to solve the security problem of anonymous authentication in vehicle ad hoc networks (VANET), we propose an efficient anonymous authentication scheme. The scheme combines certificateless password system and key insulation technique in vehicle ad hoc networks by updating the key of the road side unit (RSU) and the vehicle user . The leakage of temporary private key in a certain period of time will not affect the forward and backward security, and the security of the scheme is proved under the random prediction model. Finally, the performance analysis results show that the scheme can not only improve the efficiency of anonymous authentication of message signature, but also reduce the operation cost of the whole system, which has good theoretical significance and practical value.