Electronic throttle is a typical nonlinear device because of the nonlinear reset springs. Normal sliding mode control usually leads to chattering. To reduce chatters, a sliding mode control method based on compensation of nonlinearity is proposed, in which an observer is designed to observe and compensate the nonlinearity. A Lyapunov function was constructed to prove that control system is stable. Simulation and experiment results indicate that the proposed method can reduce chatters and achieve good control robustness.