Abstract: Experiments for the performance evaluation for the newly constructed high enthalpy expansion tunnel were carried out. Flow conditions from relatively low enthalpy to very high enthalpy, under conventional Helium driven mode and free piston driven mode, were calibrated and analyzed based on the measurements of flow field parameters such as shock velocity, static pressure and the Pitot pressure, combined with the theoretical method considering high temperature gas effects. The experiment results indicated that a free stream velocity of 11.5 km/s and a stagnation enthalpy of 71.7 MJ/kg have been achieved, with effective test time about 150 μs and 1.1 ms for high enthalpy and low enthalpy flows, respectively. This means that the high enthalpy expansion tunnel is a powerful ground testing facility, which is capable of supporting hypervelocity aerodynamics and high temperature gasdynamics researches.