Abstract：The thermochemical nonequilibrium, aerodynamic heating and aerodynamic characteristics of the hypersonic vehicle flow field are important issues in computational fluid dynamics. In typical space shuttles, during return capsule re-entrying the Earth's atmosphere, or in the process of a variety of probes entering the atmosphere of other planets, the effects of gas molecules in high-temperature flow field behind the shock wave, such as vibration excitation, dissociation, ionization and thermal radiation, are significant, because of the very high speed of vehicle, which would affect the flow field in the state of flow and thermodynamic properties. Analytical study of aerothermodynamics is an important part in the flight control and the vehicle Thermal Protection System (TPS) design. The flow fields of the Orbital Return Vehicle (ORV) aviating in the earth atmosphere with the Mach number varying from 9.7 to 27.8 were simulated in 10 cases by using the conservation integral form of Navier-Stokes equations with multi-species, nonequilibrium molecular thermal excitation and chemical reactions, based on the high-resolution Total Variation Diminishing (TVD) scheme. Aerodynamics and heat transfer of the high-temperature and high-velocity flow field behind bow shock were studied, and the aerodynamics coefficient and the wall heat flux are in good agreement with fight data. This study provides some useful data for designing vehicles' TPS.