Abstract: The HVDC cable accessory is the weak point of the cable system. In order to study the effect of the nonlinear conductivity on the charge accumulation property of SiR cable accessory insulation under polarity reversal voltage, this paper prepared a SiR composites sample by mixing the SiC particle with the SiR matrix. The three-electrode method and the surface charge measurement system are applied to obtain the conductivity and surface charge properties. The result shows that the crystal lattice vibration in SiC causes the scattering of carriers, resulting in the decrease in conductivity of sample at high temperature. The surface charge properties of SiR composites sample under polarity reversal voltage indicate that the induced electric field between the surface charges and the heteropolar charges increases the conductivity of SiR composites after the polarity reversal of corona voltage, which accelerates the transfer of surface charge into the inside and the neutralization between heteropolar charges, subsequently suppressing the surface charge accumulation.