In order to reduce the modeling complexity of the centrifugal compressor while ensuring the numerical prediction accuracy, a source term modeling method for the seal and cavity flow of the centrifugal compressor was studied based on the one-dimensional seal leakage calculation instead of the complete seal-cavity modeling. The results showed that the simplified seal and cavity modeling based on source term method could accurately reproduce the overall performance and key flow details obtained by calculation of full seal and cavity modeling, allowing only to impose the boundary conditions of leakage mass flow, total temperature and friction loss source term on the mainstream channel modeling. Compared with the complete modeling, the absolute deviation of the isentropic efficiency predicted by the source term modeling at full operating conditions was less than 0.65%, and the relative performance deviation of the total pressure ratio and the isentropic efficiency was less than 1%. The method could reduce the number of meshes by more than 50% while meeting the accuracy requirement of matching design for downstream components, and also significantly improve the economy and convergence of the calculation. The calculation accuracy of the leakage flow was the most critical factor affecting the accuracy of the performance prediction for the source term modeling method. The coupling modeling could adopt the recommended seal leakage coefficient value of the one-dimensional calculation.