The cogging force of permanent magnet linear synchronous motor (PMLSM) affects the control performance of the motor. In this paper, a novel composite magnetic slot wedge ( CMSW) based on soft magnetic and hard magnetic materials is proposed to effectively suppress the thrust fluctuation of PMLSM. Firstly, the influence of material, size and spatial position distribution of magnetic slot wedge on the output thrust and thrust fluctuation of PMLSM is analyzed. the effects of the material proportion and position distribution of soft and hard magnetic materials on the electromagnetic properties of output thrust, thrust fluctuation and cogging force are studied. Taking maximum thrust and minimum thrust fluctuation as optimization objective, the size of composite magnetic slot wedge was optimized by orthogonal optimization method. It is shown that the new composite magnetic slot wedge can effectively reduce loss and thrust fluctuations by 79. 4%, while the average thrust is basically unchanged, which provides a new technology way for thrust ripple suppression of PMLSM.