In order to meet the requirements of high precision, high efficiency and high stability of the precision measure and test appliances, the switching power supply with 0~80 V output voltage, 0~100 A output current and 6 kW output power is designed. The single-phase bridge semi-controlled rectifier filter is adopted as the former stage of the power supply, and the phase-shifted full-bridge converter is applied in the latter stage. The structure of the switching power supply and the working principles are introduced, and the calculation and selection of the key components in the main circuit are given. A prototype is developed, the experiments are carried out and the experiment results show that, the actual output voltage can track the reference voltage and meet the accuracy of 0.5% when the loads change, and the working efficiency can reach up to 87.4%.