Abstract: In this paper, a four-wheel hub motor-driven electric vehicle is selected as the research object, and the adaptive cruise control system is studied by using Matlab/Simulink and CarSim 2020. Firstly, the overall architecture of the adaptive cruise control system of the pure electric vehicle is developed, and the longitudinal dynamics of the vehicle is analyzed. Subsequently, a suitable safety distance model is selected to ensure the safety of vehicle driving, and the necessary radar and hub motor models are built through Simulink. Next, CarSim 2020 is used to build a vehicle model of the self and front vehicles as well as the simulation environment. Then, the upper-level controllers of cruise control and distance keeping are respectively built based on PID control algorithm and Linear Quadratic Regulator (LQR), and the lower-level controllers are built through vehicle longitudinal dynamics. Finally, a joint simulation model is built by Matlab/Simulink and CarSim 2020 to simulate the cruise control and the distance-keeping controller under acceleration and deceleration conditions. The simulation results show that the control system designed in this paper can realize the function of constant speed cruise and distance keeping better, and has good practicality and effectiveness.