Based on the direct torque control method of permanent magnet synchronous motor (PMSM),multiple voltage vectors were extended in the four selection areas of voltage vectors,combining with the influence law of different amplitude and phase voltage vectors on flux and torque.At the same time,according to different requirements of torque flux increase and decrease,the appropriate voltage vector group was selected.Finally,the model predictive control with variable weight coefficient was used to select the optimal vector.The simulation results show that the PMSM DTC works well by using the extended voltage vector,the flux and torque control meet the requirements,the torque fluctuation is small,the speed curve response is rapid and the fluctuation is small,and the stator flux is an ideal circle.