Abstract: In order to conduct flutter test research in hypersonic wind tunnels,a hypersonic wind tunnel flutter test apparatus and a model protection device in the form of protective cover were designed.Wind tunnel tests show that the apparatus can be used to carry out the hypersonic wind tunnel flutter test research and to prevent the test model from being interfered by the wind tunnel vibration.The protection device can work in high dynamic pressure situations and protect the model effectively.The results also validate the two ways of driving the wind tunnel with the dynamic pressure changing step by step or continuously at a fixed Mach number.In order to veri-fy the hypersonic wind tunnel flutter testing technique,flat wings flutter tests were conducted on in the hypersonic wind tunnel at Mach 5.0 and 6.0.The stochastic subspace method was used to identify structural model parameters,and the Zimmerman-Weissenburger method was used for predicting the critical flutter dynamic pressure.The results of this prediction were 12.7% larger than the calculated values using the piston theory.