GaAs/AlxGa1-xAs 2DEG samples are prepared by MBE. In the sample preparation process, by changing the Al component, the spacer layer thickness, contrast body doping and delta doping two methods, samples are analyzed by the Hall test in the 300K. It obtains the GaAs/ AlxGa1-xAs 2DEG channel structure with mobility is 7.205E3cm2/VS at room temperature, carrier concentration is 1.787E12/cm3. The THz response rate of GaAs-based HEMT structures with different channel widths at 300K and 77K temperatures is calculated by using Mathematica software. It provides a reference for the research and preparation of HEMT THz detectors.