To solve the problem of the flux ripple, big speed overshoot and slow dynamic response speed in the space vector direct torque control of permanent magnet synchronous motor, the controller of speed loop was replaced, speed loop and torque loop with Supertwisting slide mode controller based on the theory Supertwisting slide mode. The proposed control theory was simulated and verified by the software of MATLAB/Simulink simulation. The simulation results showed that the proposed control theory could successfully suppress the overshoot of speed, improve the dynamic response speed, flux and torque, and restrain the torque and flux ripple.