As an important part of intelligent transportation system, vehicle ad-hoc network technology is being concerned by more and more people. As one of the key technology of vehicle ad-hoc network, media access control technology determines how the vehicle nodes use the limited wireless channel resources, which has important influence on the performance of vehicle ad-hoc network. In order to make good use of channel resources, cooperative nodes are introduced into vehicle ad-hoc network. Then medium access control protocol based on cooperative communication is put forward. The proposed scheme is tested based on IEEE 802.11p standard. The simulation results show that proposed scheme reduces time delay and packet loss rate. It also has high throughput and has certain guiding significance to medium access control protocol design of vehicle ad-hoc network.