Abstract: The performance parameters of thermal protection system (TPS)are essential for the design and optimization of high-speed aircraft.Most of these performance parameters are ob-tained from wind tunnel assessment test.Due to the limitation of the equipment capacity of wind tunnel ,the size of the test model and the flow conditions are very different from the actual flight. The experimental data are not practicable directly and need to be converted to those under actual flight conditions based on the flight-ground conversion method.In this paper,the similarity pa-rameters in the heat conduction equation and thermoelasticity equations are discussed.The wind tunnel environment is also studied.The similarity criterion equations and boundary condition e-quations are obtained.Finally,parts of the similarity parameters in this paper are calculated and analyzed.Based on the results,the wind tunnel test can be adjusted according to this similarity criterion to improve the precision and efficiency of experiments.