Abstract: This article conducts experimental research on the effect of surface roughness of cable insulation on the interface performance between cable insulation and cable accessories. The experimental results show that the rougher the cable insulation surface, the lower the electrical strength of the interface. However, when the sandpaper used to treat the cable insulation surface reaches 1200 mesh, the roughness of the cable insulation surface is small enough, and the electrical strength of the insulation interface tends to saturation. The cable is polished and polished with finer sandpaper, The change in dielectric strength of the insulation interface is not significant.