Abstract: Due to the high stability requirement during the working process of satellite-borne multi-channel output power supply, it is difficult to establish an accurate model. This paper presents a switch network based upon averaged switch model to represent the closed-loop control model of BUCK+ half-bridge multiple-output converter. The model parameters are verified by combining with specific power supply indexes. It shows that the results meet the design requirements. The design of power control loop gives significant guidance for the engineering application of satellite secondary power supply.