For the optimization of the substrate radius of cosmetic cotton die-cutting tools produced by laser cladding, a single-factor test method was used to study the influence of the cylindrical substrate radius on the morphology and internal quality of cladding layers of the "curvilinear path trajectory on curved substrate". The results demonstate that the morphology and surface roughness of cladding layers are improved by reducing the radius of the cylindrical substrate appropriately. The cladding efficiency decreases as the radius of the cylindrical substrate increases; while the porosity of cladding layers increases with the increase of the radius, a larger radius of the cylindrical substrate produces smaller, more evenly-distributed grains and a higher hardness of cladding layers. with the highest hardness reaching 3.79 times of that of the substrate; as the radius increases to 40 mm, the cross-sectional morphology, cladding efficiency, porosity and microstructure properties become the best. The research results provide a theoretical basis for studies of the quality of laser cladding of “curvilinear path trajectory on curved substrate” for cosmetic cotton die-cutting tools and the like.