The intelligent transportation systems and vehicular networking concepts arises at the historic moment. LTE-A research and development of vehicular networking has important significance. When a mass of vehicle devices are accessed to the LTE-A network simultaneously with a full authentication and key agreement process for each device, the communication signaling would congest the network. In this paper, we proposed a cross-domain group authentication scheme. It can effectively solve the security problems. Theoretical analysis and experimental results are shown that compared with other authentication protocol, our scheme has more security properties and better performance.