AUSM (advection upstream splitting method) spatial discretization scheme was used to explore the effects of three k-ε turbulence model and second，third orders upwind schemes on shock capturing. The simulation of unsymmetrical dimethyl hydrazine/nitrogen tetroxide(UDMH/NTO) rocket engine nozzle and exhaust plume flow-field at different altitudes and Mach numbers was modeled with standard k-ε two equation turbulence model and two order upwind scheme. Afterburning was modeled with 12-component 18-chemical reaction

and the entrance parameters of the nozzle were used by thermodynamic calculation. Results showed that with the increase of flow Mach number

the wave number decreased; the plume affected area gradually expanded with the rise of altitude; afterburning reaction caused the significant decrease of O2

N2 in the mix zone while the contents of O

OH

NO in the mixing zone increased.