Abstract: When a hypersonic vehicle performs a high-altitude mission in the near space, it generates severe friction with the atmosphere, which promotes the ionization of the air around the vehicle. The plasma sheath is formed on the surface of the vehicle due to the violent friction, and it seriously interferes with the wireless communication between the radar and the vehicles, causing severe effects on the electromagnetic (EM) characteristics of the moving radar target. In this paper, the Lorentz-FDTD method is used to study the interaction between high-speed moving targets coated with plasma sheath and EM waves. The EM characteristic parameters of the moving plasma are modeled based on the relativistic principle. Based on the proposed physical model of moving plasma and Lorentz-FDTD method, the effect of the variation of the EM characteristic parameters of the moving plasma sheath on the far-field scattering properties of the radar target is investigated, and the reflection characteristics of the EM wave when passing through the plasma with different moving velocities are calculated. The research results show that the velocity of the target affects the dielectric coefficient of the plasma sheath, which changes the absorption and scattering of EM waves caused by the moving plasma. Under the influence of relativistic effect and plasma dispersion, the EM scattering properties of high-speed moving target coated with plasma sheath show different variation patterns in different EM wave operating bands.