Aiming at the problems of speed fluctuation and instability when permanent magnet synchronous motor is suddenly loaded,a sliding mode speed control method was proposed based on adaptive disturbance and novel reaching law.The state variables of the system were introduced into the reaching law,and the mathematical relation within the reaching law was improved at the same time,so as to improve the adaptive adjustment ability of the system approach speed and achieve the purpose of improving the comprehensive performance of the system.The load torque was estimated adaptively by using the Lyapunov stability criterion to make the control strategy meet the Lyapunov stability criterion,and reduce the influence of external load on the motor speed at the same time.Finally,the proposed control strategy was compared with the traditional sliding mode control strategy in the Simulink environment.The simulation results show that the proposed control method has faster response and stronger chattering suppression ability.The proposed method can effectively improve the overall performance of the system and achieve more stable speed control.