Since rotor structures of the IPMSM are different from the common motor, inductance parameters are hard to be accurately calculated by the traditional calculation method. A new analytical method, which is called the fixed permeability method (FPM), is used to calculate the inductance parameters and the magnet flux λm of IPMSM. The results calculated by the FPM and the conventional finite element method (FEM) are compared and the reasons which caused the different results are analyzed. The impacts of saturation and cross coupling on the inductance and the magnet flux λm and the impact of the width of the bridge on the inductance are studied. On the basis of the analysis, the influence factors and the rules of the inductance parameters of IPMSM are summarized, which are good for analysis and design of PMSM.