In this paper, the vector control system of permanent magnet synchronous motor is studied. The backward control is introduced into the traditional vector control, and a backward controller is designed to meet the stability of Lyapunov function, which solves the defects of the traditional PI control, such as poor anti-interference performance and slow dynamic response speed of the system. Finally, using Matlab/Simulink platform to establish a simulation model, simulation experiment analysis. The simulation results show that the backsliding control algorithm improves the response speed of the speed loop, simplifies the control design of the system, ensures the asymptotic stability of the system, and realizes the control of the speed.