Spacecraft power systems are used to generate, store and transform electrical energy and involve mechanical, electrical, thermal and information fields. In this paper, the MWorks multi-domain simulation platform in Modelica language is used to build models of solar arrays, shunt regulators, charge/discharge regulators and bus filters, and the individual models are assembled to obtain the spacecraft power system model. Simulation and analysis of the models were carried out to verify the correctness and feasibility of the system design.