The power supply system is an important component of the satellite, providing continuous and stable energy for satellites on orbit. Establishing a digital accompanying flight model for the satellite power supply system is of great significance for the monitoring, simulation, control, and prediction of its on-orbit status. Aiming at the problems of low fidelity and difficulty in virtual and real synchronization of existing models, a modeling method for digital accompanying flight of satellite power supply systems is proposed. Firstly, a high-fidelity mechanism model of the satellite power supply system is established through the circuit equivalent method, mathematical equivalent method, averaged model-state space and small signal method and others. Secondly, in order to obtain the dynamic input and output, the methods that telemetry data dynamic parameter identification and parameter extraction are used, thereby driving the dynamic update of the mechanism model. Finally, experiments were carried out using high-orbit remote sensing satellites to verify the digital accompanying flight of the model. As shown in the experimental results, the typical output parameters of the digital flight simulation model presented in this paper demonstrate an accuracy exceeding 95% . Moreover, the model can achieve virtual and real synchronization mapping and digital accompanying flight with on-orbit satellites every 0. 5 seconds.