Abstract: The inlet shroud is widely used in high-speed vehicles since it can avoid unstart phenomenon under the low Mach number flight condition. As the separation process directly determines the safety of the flight vehicle, it is necessary to testify the separation process in the ground testing. In this paper, the advantage of the JF-12 shock wind tunnel is utilized fully to develop the high-speed separation testing technique. The similarity criterion which is suitable for the high-speed separation is deduced for three testing purposes. The observation and identification methods are developed for the high speed separation trace. A set of the high-precision sequence control system is built. Some protection measures are adopted to avoid the risk from the high speed shroud. Using these techniques, a typical 2-dimensional forebody/inlet with the shroud was used for the separation testing in JF-12. The separation trace under the freestream condition of dynamic pressure 100kPa is obtained successfully by the testing freestream of dynamic pressure 50kPa.