Reasonable selection of pole-slot combination is a key part of electric machinery design. In order to solve the problems of time-consuming and resource-consuming caused by repeated modeling with traditional finite element technology, an analytical model of permanent magnet synchronous motor is established to analyze the influence of different pole-slot combinations on motor performance. In 2D polar coordinate system, the motor is divided into four regions: armature slot, stator slot opening, air gap and permanent magnet. Then, the Laplace equation or Poisson equation of each sub-domain is constructed. The sub-domains are analytically calculated by combining the variable separation method with the boundary conditions, and the construction of the motor’s analytical model is completed accordingly. The correctness of the analytical model is verified by the finite element method. Using the analytical model, the effects of different pole-slot combinations on the performance of the motor are studied. The results show that the 60-slot-8-pole motor has better performance of output torque with much smaller cogging torque than the others. The load radial air gap flux density of fractional pole-slot combination is more sinusoidal than that of integer pole-slot combination, which can effectively reduce torque ripple. Within a certain range, multi-slot structure is beneficial to promoting the performance of motor’s output torque.