Abstract: Three-dimensional Navier-Stokes equations in real gas models are solved with a parallel code to analyze aerodynamic characteristics of Mars Science Laboratory in hypersonic entry in Martian atmosphere. Good agreement between numerical results and flight data of Viking validates physical-chemical models and numerical methods. It shows that impacted by real gas effect,shock layer thickness is reduced; drag coefficient rises,lift coefficient is almost unchanged. Difference of trim angle between real gas and perfect gas is about 2.2°; As keeping altitude,greater Mach number results in greater drag and pitching moment coefficient. Difference of trim angle varies from 1.6° to 2.6°. Increasing Mach number enhances real gas effect. As keeping Mach number,increasing altitude weakens chemical reactions behind the shock,but it has weak influence on aerodynamic coefficient.