Room temperature vulcanizing (RTV) silicone rubber coating with superhydrophobicity for anti-pollution flashover is prepared by filling silica-encapsulated calcium carbonate particles (CaCO3/SiO2 composite particles) into polydimethylsiloxane (PDMS) rubber. Two-step spraying technology is applied for fabricating the superhydrophobic RTV coating film on outdoor insulators. The primary spray coating provides basically the strong adhesion and certain hydrophobicity, and the second one produces the appropriate roughness structure and further enhances the superhydrophobicity. The water contact angle on the prepared RTV coating film is 165°and the sliding (rolling) angle of water droplet is about 5°, allowing water droplets to move easily on the coating surface and give self-cleaning function of the RTV coated insulator surface. The flashover voltage of insulators with superhydrophobic RTV coating is 29.95 kV, quite higher than that of insulators with common RTV coating (23.29) and that without RTV coating (11.34 kV).