Contact morphology of the solid-solid composite insulation interface is the key to determine the insulation level of cable accessories. In this paper

a mesoscopic contact-characteristic analysis model of the XLPE-SiR interface is established based on the hyperelasticity constitutive relationship and the equivalent roughness method

and the accuracy of the analytical model is verified by internal contact interface observation of an actual XLPE-SiR interface sample. Then based on this model

the influence of surface roughness and contact pressure on the internal contact characteristics

such as the actual contact area ratio and cavity size

is studied. Finally

with the interface breakdown experiment

the influence of the interface contact morphology on the interface breakdown strength is explored. It is found that the actual contact area ratio of the solid-solid composite interface decreases exponentially as the material surface roughness increases

but increases linearly as the interface pressure increases. With the increase of the actual contact ratio of the interface

the interface breakdown voltage increases exponentially

while the breakdown voltage dispersion increases first and then decreases.