In order to solve the control problem that the permanent magnet synchronous motor is sensitive to the external load disturbance and parameter variation, a sliding mode control method based on extended state ob- server and exponential reaching law is studied. The extended state observer is designed, and then the sliding mode control based on the extended state observer and approaching law is established respectively, and the bi- poler S-type function is used instead of the symbolic function to weaken the chatter in sliding mode. Finally the stability is proved. The simulation results show that ...