Abstract: In view of problems of low accuracy of rotor position angle estimation, large computation, poor stability and anti-disturbance performance when sensorless control was used in speed regulation of permanent magnet synchronous motor of mine-used electric locomotive, an improved model reference adaptive system was proposed. Adaptive law is simplified according to zero direct axis current, so as to reduce complexity of calculation. Sliding mode controller is used instead of PI regulator to control speed loop, so as to reduce disturbance influence. The simulation and experimental results show that the method can accurately estimate rotor position angle, reduce speed fluctuation, and has good stability and anti-disturbance ability.