In order to improve handling stability of an in-wheel-drive electric vehicle， influences of the vehicle yaw rate and the sideslip angle on the vehicle stability are analyzed theoretically. A double-layer controller based on sliding mode control theory and direct yaw moment control is designed. A four-wheel-driven vehicle simulation experiment platform built in Carsim and Carsim / Simulink co-simulation is carried out. In standard lane-change condition， the improved effects of sliding mode control strategy based on sideslip angle and the control strategy based on yaw rate are verified and the effectiveness， confirming robustness of the two-layered stability control strategy proposed.