The Vehicular Ad hoc NETwork （VANET） improves road traffic efficiency， but the security and privacy issues it faces may lead to serious traffic accidents， making anonymous authentication of messages necessary. However， existing authentication schemes still struggle to the problems of conditional privacy preservation， anonymous authentication and authentication efficiency. To address these problems， a conditional privacy-preserving authentication scheme for VANET based on certificateless group signature was proposed. Firstly， an anonymous authentication scheme based on certificateless group signature was proposed by combining certificateless public key cryptosystem with the ACJT group signature algorithm. In this scheme， when group member changes， other group members remain unaffected and require no key updates； moreover， the computational overhead of the group signature generation and verification algorithm remains constant， independent of the group member number. Furthermore， to prevent vehicles from committing malicious acts due to identity anonymity， the scheme realized conditional privacy protection， i.e.， when a malicious act occurs， the identity of the relevant vehicle can be traced and held responsible. Security analysis proves that the scheme simultaneously satisfies forward security， unforgeability， and unlinkability requirements. Performance experimental results show that compared with similar schemes， the proposed scheme improves the authentication efficiency by at least 31.63% and reduces the communication overhead by at least 33.12%.