Abstract: The paper proposed a sensorless vector control method for permanent magnet synchronous motor at zero or low speed. Accurate position and speed of rotor in sensorless vector control were estimated by injecting high-frequency signals into two rotate coordinate based on saliency effect principle of motor, then it gave a sensorless vector control system for permanent magnet synchronous motor. The simulation result showed that the method can accurately estimate rotor's position and speed and meet the need of vector control of permanent magnet synchronous motor.