<p>Film cooling shows significant potential for mitigating the “blackout” effect caused by plasma sheaths. In this paper, the influence of cooling gas film on the key characteristic parameters (electron density and collision frequency) and electromagnetic transmission characteristics of the plasma sheath are studied by controlling the shoulder of the aircraft to spray cooling gas to simulate energy injection and absorption. The results show that under hypersonic flow conditions, the electron density increases due to the dissociation of the counterflow jet medium and diffuses downstream over the vehicle body. The cooling gas film can be formed on the target wall by spraying CO₂ and N₂ through the shoulder, the electron density and plasma frequency on the wall decreases. Notably, the plasma collision frequency increases to varying degrees due to the dissociation of the injected particles. Under N₂/CO₂ film cooling, the Maximum attenuation intensity of electromagnetic wave is reduced by 15dB, the resonant frequency of electromagnetic wave and plasma sheath is increased. This study provides valuable insights for designing physical and chemical interventions to regulate the spatial distribution of plasma and the research of anti-black barrier communication.</p>