Abstract: In this paper,a thermal shock test method of thermal protection structures is introduced. The rationality of closed cavity thermal test is discussed. The specific operation process in the test is given,and the real and reliable test data are obtained. The test results show that air interlayer can effectively promote thermal insulation performance of thermal protection structure. The thickness of air interlayer is proportional to the decrease of the temperature rise of the bottom plate. The more severe the thermal load of the structure surface suffers,the more significant the inhibition of the bottom plate temperature rise by unit thickness air interlayer is. The influence of bottom plate temperature rise by unit thickness air interlayer declines with increasing bottom plate thickness. This rule can provide experimental basis for the design of efficient thermal protection structures.