Due to compression and pyrogenation by shock wave, plasma sheath is formed around the surface of vehicle when hypersonic aerocrafts fly in near space. Plasma sheath can absorb and reflect electromagnetic wave radiated by the antenna on the vehicle. In order to analyze transmission property of plasma sheath, transfer matrix method is introduced. Based on the typical vehicle model and fundamentals of computational fluid dynamic, the Navier-Stokes equations are solved and electron density distribution in the plasma sheath is obtained. On the basis of propagation theory of electromagnetic wave and correlative characteristics of plasma sheath, the attenuation coefficient of electromagnetic wave in plasma sheath is diagnosed. On the other hand, propagation characteristics of electromagnetic signals which mainly include refection and transmission coefficients are analyzed. Analysis results show that good agreement is achieved among numerical results of transfer matrix method, theory analysis results and simulation results of FDTD (Finite Difference Time Domain). It is proved that the proposed method dramatically decreases computation complexity and is suitable for any kind of electron density distribution and thickness of plasma sheath.