Abstract: The mass injection of ablating gas flow affects the stability of boundary layer and the transition location during the ablation of thermal protection materials on a reentry vehicle. In this paper, an experimental method of ablative gas mass injection in a wind tunnel is studied. According to the principles of pipeline gas flow and porous material permeability, the mass flow of ablative gas is simulated. The mass flow of gas is controlled by proportional valve and flow meter, and the transition location is measured by the infrared imaging technology. The experimental research is carried out on the blunt cone model under Ma = 6 and Re = 2.5 × 10⁷ m⁻¹ conditions. The results indicate that the technology simulates the ablative gas mass injection of a reentry vehicle effectively, and the mass injection can promote the transition: the transition location moves forward with the increasing mass flow of ejected gas. The experimental technique can provide important data for the overall optimization and design of related aircraft.