This paper aims to reduce detent force (DF) of a moving-magnet-type linear synchronous motor by considering different permanent magnet (PM) widths and chamfer dimensions. DF is the main cause of thrust ripple, which can lead to worse operation performance. Through Fourier decomposition, it is found that the PM size is the key factor affecting DF significantly. The thrust and its ripple of different PM widths are obtained by using the finite-element analysis. After selecting the optimal PM width, considering the mechanical strength factor, the PM can be unavoidably chamfered, which further influences DF. Based on this, an optimized motor model is designed. The prototype is manufactured to verify its results.