The influence of using the Martian atmosphere while simulating jet flow to analyze aerodynamic characteristics of Martian aircraft were studied.Aerodynamic characteristics of slender body aircraft calculating with or without the flow of a jet under Martian atmosphere are also studied using computational fluid dynamics（CFD）.Conclusions have been drawn as follows.While using Martian atmosphere to simulate Martian aircraft，the axial force coefficient under this circumstance is larger，pressure center is more stable.In Martian atmosphere，jet flow will significantly change the aerodynamic characteristics of Martian aircraft，while influencing the surface pressure distribution and downstream region.If simulating jet flow in Martian atmosphere，before Ma=5.0 the axial force coefficient is smaller，while after Ma=5.0 it is larger than the condition without the jet flow.There is a sudden reduction on axial force coefficient and pressure center coefficient during the transonic region while simulating with the jet flow.