A quasi-one-dimensional numerical simulation method is developed to investigate the flow of a piston-driven high-enthalpy expansion tube, taking into account high-temperature and high-pressure real gas effects, wall friction and heat transfer, and piston dynamics. The method well reproduces the overall characteristics of the tube flow and the test flow condition. The results indicate that the non-uniformity of the test flow is mainly caused by the wall transport effects and is further exacerbated by the incomplete action of the rarefaction wave in the acceleration section. It is also found that the high-pressure gas effect and the high-temperature gas effect act separately in different regions. The former mainly occurs in the piston compression section, causing a slight delay in the overall flow. The latter, which is far more pronounced, occurs in the shock-compressed regions, causing a weakening of shock wave and a significant decline in temperature. A quasi-one-dimensional numerical simulation method is developed to investigate the flow of a piston-driven high-enthalpy expansion tube, taking into account high-temperature and high-pressure real gas effects, wall friction and heat transfer, and piston dynamics. The method well reproduces the overall characteristics of the tube flow and the test flow condition. The results indicate that the non-uniformity of the test flow is mainly caused by the wall transport effects and is further exacerbated by the incomplete action of the rarefaction wave in the acceleration section. It is also found that the high-pressure gas effect and the high-temperature gas effect act separately in different regions. The former mainly occurs in the piston compression section, causing a slight delay in the overall flow. The latter, which is far more pronounced, occurs in the shock-compressed regions, causing a weakening of shock wave and a significant decline in temperature.