The high-temperature jet flow from the scramjet nozzle has a great influence on the aerothermal environment of hypersonic vehicles. In order to develop the experimental technique to analyse the small-scale model aerothermal environment in the impulse wind tunnel, a high enthalpy gas supply platform was built. It used the oxyhydrogen burner to drive the Ludwieg tube to produce the high-temperature gas jet flow. This paper presents the research on the influence of different hydrogen-oxygen proportions on the generation of high-temperature gas jet flow and the influence of different generation methods on the stability of the high-temperature gas jet flow, including the ignition methods and the diaphragm splitting methods. The platform can generate high-temperature gas which has different thermodynamic states to satisfy the small-scale model experiment similarity criterion, and can be started in 50 ms and work together with the impulse wind tunnel.