Abstract: Traditional direct torque control adopts circle-flux control with six-section and has large torque ripple and bad control performance.When influence of voltage drop of stator resistance is considered,its section chosen has disadvantage.Aiming at above problems,the paper proposed direct torque control strategy based on twelve voltage space vectors.It established direct torque control system of twelve voltage space vector of permanent magnet synchronous motor,made corresponding on-off principle and adopted sliding mode variable structure to design speed regulator,which replaced traditional PI regulator in order to enhance robustness performance of anti-interference and resisting parameter distortion of the system.The simulation results showed that stator flux and torque ripple of the system are small and dynamic and static response of the system are good.