This study simulated spent fuel assemblies using alumina ceramic core rods and 304 stainless steel cladding and investigated the effects of various laser cutting process parameters on cutting quality. Based on cutting seam width, cutting surface roughness, and slag hanging length, a fiber laser with a maximum power of 12 kW was used to assess the cutting performance. The effects of various parameters on cutting quality were systematically analyzed under different laser powers, cutting speeds, defocus amounts, and cutting auxiliary air pressure conditions. Results indicated that the best cutting performance was achieved with a laser power of 9.6 kW, cutting speed of 0.7 m/min, defocus distance of -10 mm, and cutting auxiliary air pressure of 15 bar. The cutting width, slag hanging length, and section roughness were 1.89 mm, 1.2 mm, and 27.4 μm, respectively. This study provides valuable experimental data and technical insights for optimizing spent fuel laser disintegration technology.