Abstract: According to the implicit numerical integration method proposed by Tyson.J,an improved computer program for pseudo one dimensional flow of combustion kinetics is developed with the aid of a chemical kinectic model with 12 species and 31 reaction.Variations of temperature,prssure,Mach number and mass fraction of chemical species in a supersonic combustion model are studied in detail.The results of scramjet combustor conditions corresponding to flight Mach numbers 6,10 and 15 show that chemical reaction rates decrease at rather low temperature and pressure at a combustor inlet and there is not enough time to ignite the mixture gas in the combustor at very high Mach number,in result the performance limits of scramjet kinetic combustion occur.