Predecessors take cooperative downloading method to solve this delay issue, while this method need mutual cooperation between vehicles, but a incentive mechanism for this cooperative downloading method still has not been put forward. This paper based on cooperative downloading method to design the incentive mechanism, to encourage cooperation between vehicles, and help users to receive the needed resources effectively. For describe the design of incentive mechanism, this paper first analysis the characteristics of the highway scenarios and cooperative downloading method. Finally propose the incentive mechanism, and illustrates how this mechanism works.