To improve the steering portability and the returning ability of steering wheel，the research on differential assist steering and returning control using the torque difference between left and right wheels is carried out.Firstly， the steering system model is used to predict the steering wheel torque， and the ideal assist torque at different vehicle speeds is calculated according to the assist characteristic curve， then the ideal steering wheel torque is obtained from both.The deviation between the measured steering wheel torque and the ide-al steering wheel torque is taken as the control target， and the differential assist torque is obtained.With the goal of achieving differential assist torque and the constraint condition of lateral stability， the wheel drive torque is optimally distributed based on the quadratic pro-gramming method to realize the differential assist steering control.According to the charac-teristics of steering wheel angle， a combination method of differential assist steering and re-turning controlisproposedfinally.The co-simulationbasedon CarS imand MATLAB proves that the proposed method can improve the vehicle steering portability and the retur-ning ability of steering wheel.