The mount drive control is the largest technical challenge which affects the telescope’s resolution and speed mostly. However, the ultra-lower speed and the giant moment

of inertia make the mount drive of the telescope very difficult to be controlled. In this paper, one arc permanent-magnet synchronous motor (PMSM), 2.5m diameter, is suggested for the mount driving. A large aperture radio telescope project will use direct drive to realize the azimuth and elevator axes driving. As to the motor, a method is presented to drive the motor directly, which is based on 32bits fixed-pointed processor TMS320F2812 and Intelligent Power Module (IPM), also, ADS8361 is used to detect the phase current of the stator windings. The arc PMSM can work stable and the mount drive can realize nice tracking performance at ultra-lower speed with this drive circuit.