A bisphenol A epoxy-modified silicone rubber was prepared by the chemical grafting, and the structure of modified-silicone rubber was characterized by FTIR. The effects of catalyst and epoxy resin content on the mechanical property of modified-silicone rubber as well as its curing system were investigated. The modified-silicone rubber was used in the external thermal protection coating of the solid rocket motor, and the coating performance was assessed by the supersonic arc wind tunnel experiments. It is found that the appropriate addition of etraisopropyl titanate could improve the mechanical property of modified-silicone rubber during the preparation. In addition, the mechanical properties of silicone rubber obtained increased with the epoxy content. When the epoxy content exceeded 20wt%, the tensile strength and the bonding strength of the rubber are greater than 2 MPa and 3 MPa, respectively. RCA-polyamide 650 composite curing system can be used to cure the modified-silicone rubber. The results show that the structure of the coating sample is integrity, and the back wall temperature of the coating sample is below 152℃ after wind tunnel experiments.