The traditional PI speed controller of has the disadvantages of speed overshoot, long dynamic time, low tracking precision, poor ability of load torque disturbance and recovery. A speed controller was proposed. It was based on the motion equation and the torque equation of the permanent magnet synchronous motor to derive the qaxis current of the control system. A speed controller of permanent magnet synchronous motor was designed according to the Lyapunov stability condition. Compared with the traditional PI speed controller, the controller had no speed overshoot, short dynamic time and high tracking precision, and improved ability of load torque disturbance and recovery. By using MATLAB/Simulink simulation software, the control system model was built and the simulation analysis was carried out. Simulation results showed that the speed controller of PMSM was effective, and it could get a good speed control performance.