To improve the heat resistance of sealer coating，high-temperature resistant sealer coating was prepared by using silicone rubber as matrix material with the addition of cyanate ester and kaolin as dispersants to seal the thermal spraying coating. The dispersion of various fillers in the silicone rubber matrix was observed by scanning electron microscope，and the heat resistance of the sealing coating was characterized by thermogravimetric analyzer. The heat-corrosion resistance of the coating was studied，and the sealing effects of different coating were compared and analyzed. The results showed that，compared to the silicone rubber coating，the heat resistance of the modified silicone rubber coating was improved considerably. Both cyanate ester and kaolin could improve the heat resistance of silicone rubber sealing coating to a certain extent，which in turn affected the sealing effect and heat-corrosion resistance of the composite coating.