Abstract: To improve the computational efficiency of airbreathing hypersonic vehicle's flowfield,a combined computational fluid dynamics(CFD) method,which combines space marching method for parabolized Navier-Stokes(PNS) equations and time iteration method for Navier-Stokes(N-S) equations,was used to simulate airbreathing hypersonic vehicle's flowfield.Space marching method was used to solve the PNS equations in the supersonic dominated regions,and time iteration method used to solve the N-S equations in the stream direction separation or subsonic dominated regions.For solving the two-dimensional(2-D) airbreathing hypersonic vehicle's flow field with chemical reaction,the combined CFD procedure can get the same results with the same accuracy and also improve computational efficiency for several folds as compared with traditional time iteration methods.