In order to meet the requirements of vehicle photoelectric theodolite on the control precision, stability, weight and volume of the servo control system, relevant research is firstly carried out on the main power supply of the servo control system. As the energy supply unit of the servo control system, the stability of the main power supply determines the stability of the servo control system. Then the tracking precision and tracking frequency of the servo control system are affected. In this paper, the design requirements of the power supply, the main circuit, the maximum pulse width limiting circuit, PWM control circuit, voltage and current detection circuit and voltage feedback control circuit are described. At the same time, the design of the power supply according to this method, the test results are obtained: the power output is 48V DC; The output power is 2400W; Peak-to-peak value is 310mV; Weight: 13.8kg; Volume: 350*200*110 mm3; Meet the power supply design requirements of the equipment.