Direct torque control (DTC) has been widely used due to its advantages of less parameter dependence and faster torque response. However, in conventional DTC, there are obvious torque and flux ripples. This paper studies the influence of zero space voltage vectors on DTC system of permanent magnet synchronous motor (PMSM). The control model is established with Matlab/Simulink software. The simulation results show that the ripple torque can be reduced significantly when zero space voltage vectors are used. Meanwhile, the use of zero space voltage vectors can evidently decrease the switching frequency of the power switches as well as the switching loss. The achievements in this paper can provide a reference to improve DTC performance of PMSM.