The anti-icing and de-icing methods of insulator strings are still under laboratory studies while many technologies are applied in operation to overhead conductors. The anti-icing method using semiconducting silicone rubber coating applied to the bottom side of the insulators could get good results in a climate chamber. However, the resistance of the coating is an important factor influencing the anti-icing performance of the coated insulators. Thus the coating resistance should be determined. A heating analytical method of insulators with semiconducting silicone rubber （SIR） is proposed.