Size of laser facular control unit in laser target simulation system for guided munitions was studied. According to the design index that this system requires for variation range, the maximum rate of changes and control accuracy of the field angle of facular, mathematical model of size of laser facular control unit was established. Then, servo control system with unidirectional limited angular position was composed of an ELMO driver-controller and a DC torque motor，as a result, current feedback, velocity feedback and position feedback made the closed loop control be realized inside the system. Experimental results of the system testing indicate that closed loop servo bandwidth of the DC torque motor is 82.1 Hz，and field angle of facular changed from 0.5 mrad to 5 mrad is 112.1 μrad, which is less than 0.15mrad that the design requires. The maximum error of the field angle of facular changed from 5 mrad to 90 mrad is 326.1 μrad, which is also less than 0.5 mrad that the design requires. Within the variation range of the field angle of facular, its error is in the designed reasonable error range, which can ensure that the control strategy meets the performance requirement of system.