In this paper, a coupled electric-thermal model is proposed to estimate the power loss and thermal performance of power module and three-phase inverter. First, the electrical extraction software is used to obtain parasitic parameters of the package. Then, the temperature field of the package is simulated under certain power by using computational fluid dynamics (CFD). Finally, the results of the electrical extraction and the CFD model are imported into the circuit simulation software to establish an equivalent circuit model for coupled calculation of conduction loss and switching loss under certain boundary condition. The results of the power loss and temperature field are also compared with the experimental data.