Aiming at the problem that the dynamic quality of the speed regulation system of permanent magnet synchronous motor is easily affected by uncertain factors such as parameter changes,external disturbances and friction,an improved exponential reaching law was proposed.For the parameters k and ε in the reaching law,fuzzy rule control was introduced to effectively suppress the inherent chattering problem in the traditional sliding mode variable structure control and improve the convergence speed.In order to eliminate the control accuracy problems caused by internal and external disturbances of the system,a new disturbance observer was designed for observation.The simulation results show that this method can achieve accurate speed control； compared with the traditional sliding mode control,the sliding mode chattering is effectively reduced on the basis of retaining its advantages.