In this paper, the high-efficiency thermal insulation composites were prepared and investigated, which are formed by the addition of hollow SiO2 microspheres, hollow glass microspheres, and hollow phenolic microspheres into addition-type liquid silicone rubber. The thermal conductivity of composites is as low as 0.054 W/(m·K), which is 70.65% lower than the matrix (the thermal conductivity of the matrix is 0.184 W/(m·K)), and the tensile strength is 1.003 Mpa, and the thermal decomposition temperature of the composites is 427 °C .