The effect of different slot numbers on the permanent magnet synchronous motor with less rare earth combined magnetic poles (LREH-PMSM) is explored. In this study, the stator slot sizes are reasonably designed while keeping the same copper mass of the winding and armature current, and the LREH-PMSM 2D simulation models of 24 slots, 36 slots and 48 slots are constructed by the finite element method. By comparing and analyzing the simulation data of LREH-PMSM model with different slot numbers in terms of magnetic flux density distribution, magnetic flux lines, no-load back electromotive force (no-load back EMF), air gap magnetic flux density, electromagnetic torque and cogging torque, it is found that compared with 24 slots and 36 slots, the 48 slots LREH-PMSM can improve the torque and torque fluctuations, so as to optimize its output performance.