Abstract: When the maglev train with electromagnetic suspension technology is running at high speed, a sensorless control algorithm is needed to estimate the speed and position of the train to ensure the stable operation of the maglev train. The long stator linear synchronous motor was taken as the research object. For the double-end power supply mode of high speed maglev, the theory of reduced-order observer was used to realize the speed sensorless control of the linear motor. Firstly, the mathematical model of long stator linear synchronous motor was given and written as the state equation; the back EMF observer of linear motor was designed by the theory of reduced order observer; the angular deviation was obtained from the back electromotive force components; finally, the angle and speed of the motor could be obtained from the PI regulator. The scheme proposed in this paper was verified on the semi-physical simulation platform.