Aiming at the problems of low precision control accuracy, large torque ripple and unstable switching frequency in traditional direct torque control (DTC) method, a DTC method based on second order sliding mode control for permanent magnet motor was proposed. Based on the second order sliding mode control principle, traditional flux controller and torque controller were replaced by sliding mode controller. Vectormodulating method was used to modulate the space voltage and the stability of switching frequency was improved. Also, dynamic and output performances of motor were improved. The simulation and experimental results showed that the control method could effectively reduce the current ripple and torque ripple. The antiinterference ability of control system was enhanced. The fast dynamic response and strong robust performance of motor were realized.