In order to solve the problem of uncertain internal parameters and unknown external disturbances of permanent magnet synchronous motor (PMSM), a nonlinear control method based on nonlinear smooth extended state observer (ESO) was proposed. By introducing the non linear smooth function, the ESO was designed to observe the internal and external uncertainties of PMSM. The observational results were compensated to the non linear controller in real time, which improved the dynamic and static performance and antidisturbance ability of the motor effectively. Sliding mode controller based on non linear smooth function was used to replace the hysteresis controller in traditional direct torque control (DTC), which effectively weakened the chattering and pulsation of the torque and flux linkage. The simulation results showed that the method has fast response, good stability, strong antidisturbance ability, and good robustness.