Abstract: During the flight of hypersonic aircraft, due to the impact of high temperature and high pressure, a layer of plasma sheath is formed on the surface of the aircraft. With the aircraft and its plasma sheath motion at high speed relative to the ground measurement and control center, a serious impact on the electromagnetic echo of the target will be caused. In addition, the time-varying characteristics of plasma sheath also modulate the radar echo of the target, making it difficult for the center to identify and track the target. In this paper, Lorentz-FDTD method is used to study the interaction between the relatively moving plasma sheath and the electromagnetic wave, and the influence of the relative motion and time-varying characteristics of the plasma sheath on the electromagnetic wave is analyzed. It is found that the moving time-varying plasma not only causes Doppler shift to the electromagnetic wave but also modulates the spectrum of incident wave.