Abstract: In the adaptive cruise control system, fuel economy can be improved by changing the driving strategy. For cruise mode following the fuel economy of vehicles to improve the problem, this paper USES dynamic programming strategy, considering the acceleration time short and sliding mode is helpful to improve fuel economy, the acceleration and velocity in a bounded domain, the optimal control algorithm, and in a given speed range, improved fuel economy of the optimal acceleration and deceleration strategy. In order to verify the effectiveness of the algorithm, a simulation platform was built and relevant simulation experiments were carried out. Simulation results show that the proposed control method can optimize the vehicle fuel economy and determine the optimal shift time.