Abstract: Aiming at the stability control of two-motor four-wheel driving electric vehicles，this paper adopts the hierarchical control method to coordinate the driving torque of the electric motor on anterior-posterior axis and the hydraulic braking torque，and thus obtains the adjusted yaw moment，so that the vehicle stability is ensured and the driving speed is meanwhile improved． In the upper control system，through the variable-structure synovial control，the longitudinal force and the adjusted yaw moment are obtained to ensure the vehicle stability． Moreover，the index reaching law is designed and the saturation function is used to replace the sign function，so as to achieve the quasisliding mode and attenuate the high-frequency chattering． In the lower control system，the quadratic programming method is employed to achieve an optimal distribution of the electric motor drive torque and the hydraulic braking torque． The whole vehicle and controller models are constructed by combining Avl Cruise，Carsim and Matlab/Simulink，and  corresponding experiments are conducted． Simulation results show that the proposed control strategy can
improve the ability of vehicles to track the road，decrease the side slip angle and improve the dynamic response performance of vehicles．

Key words: electric vehicle, control, 4WD, stability, hierarchical, sliding mode