In this paper, the magnetic circuit characteristics of a surface permanent magnet synchronous motor (PMSM) are analyzed, and the equivalent magnetic network model based on the nodal magnetic potential equation is established. In order to realize the fast calculation of magnetic properties of the motor, the iterative calculation program of nonlinear magnetic network model is written by MATLAB. The program is based on nodal magnetic potential equations and uses iterative algorithm to solve nonlinear equations, which can efficiently calculate the magnetic field distribution and performance characteristics of the motor. Compared with the traditional finite element method (FEM), accuracy of magnetic network model (MNM) and the advantage of efficiency are verified.