The invention discloses a digital control system for a satellite aerial directing mechanism which is applied to driving and controlling a novel high-precision reliable satellite aerial directing mechanism. The system comprises a digital signal processor (DSP), a synchronous machine, a rotary transformer, a Hall effect rotor position sensor, an exciting output circuit, an axial angle decoder circuit, a three-phase bridge type power module, a PWM driving circuit, a three-phase winding current detecting circuit, a communication module circuit, a secondary power supply transfer circuit, and a protection circuit. The system can realize the high-precision control for the satellite aerial directing mechanism by the upper computer communication, the output shaft position detection, the winding current detection, the motor rotor position detection and a series of control methods.