Suspension， as a connection structure system among the body， frame and wheels， has a great effect on vehicle ride comfort， handling stability， and driving comfort. As the new active suspension system can improve driving comfort， prevent fatigue of the driver， and ensure vehicle control authority under extreme working conditions， a quarter active suspension model of in-wheel-drive electric vehicles is established. A sliding mode controller（SMC） of an electromagnetic actuator-based active suspension is also designed， in which stability of the system is proved using Lyapunov criterion and the chattering in SMC is reduced by adopting the reaching law method. Simulations on B-level road and bump excitations are implemented to verify the performance of the designed controller-based the active suspension system， regarding the vertical acceleration of the vehicle body， the suspension dynamic deflection， and the tire dynamic load. The results show that the SMC can reduce the impact on the vehicle body and significantly enhance the vehicle driving comfort and ride comfort.