Combined energy equilibrium equation and two thermal flux approximation methods were used to establish the steady heat transfer mathematic model of the multi-layer thermal insulations in the metallic protection system.Radiation attenuation index of fibrous thermal insulations and emissivity of heat insulation screen were optimized by genetic algorithm and experiment that measured the effective conductivity of the multilayer thermal insulation element.The experimentally measured effective conductivity data of the multi-layer thermal insulations validate steady heat transfer model of the multi-layer thermal insulations

which adopt optimized thermal physical parameters.