The influences of pressure are not considered when testing the conductivity of semiconducting water-blocking buffer layer of HV cable. The surface resistance characteristics of buffer layer under different pressure are studied. Firstly, the surface resistance of buffer layer are tested, the statistical characteristics of which are explained through microstructure characteristics and nano-filler conductive mechanism. By applying loads of different weights on the surface resistance test electrode and the buffer layer between the electrodes, the relationship between the resistance value of the buffer layer and the external pressure is studied. Based on n-order resistance network and difference equations, the surface resistance model of buffer layer under pressure is established. The microscopic piezoresistive property of buffer layer and the simulation calculations of its model are used to analyze the characteristics of surface resistance test and the change law under different pressure. The results are helpful to understand the conductive characteristics of the buffer layer of HV cable under real operating pressure.