Vehicle applications makes the requirements on Vehicle-to-Roadside(V2R) communication quality and system throughput more and more higher. V2R communication power allocation strategy is proposed to improve the quality of communication links and the system throughput. The strategy adopts the game theory to analyze the power allocation process and find out the optimal allocation scheme. When the utility function reaches Nash equilibrium through iterations, it indicates that the system has obtained the optimal power allocation scheme. Simulation results show that the proposed power allocation strategy is helpful to reduce the interference between communication links, and the purpose of improving the system throughput is achieved.