Aiming at the problems of chattering and poor dynamic and static characteristics of traditional sliding mode controller (SMC), an SMC based on weighted integral gain is proposed. Based on the traditional exponential reaching law, the new reaching law introduces the weighted integral gain, and the accessibility of the sliding mode surface is verified by Lyapunov theorem. The weighted integral gain SMC, the traditional SMC and the integral gain SMC are compared. The simulation results show that the proposed weighted integral gain SMC can suppress the chattering of SMC and reduce the sliding mode observer estimation variance, and it has quickness and the insensitivity of external interference. The effectiveness and superiority of the control strategy are proved.