Abstract: Since pulsatory supply of fuel in operation of turbojet engines deteriorates both combustion and turbine efficiencies and makes them deviate from data given by characteristic maps.Moreover,it is also hard to obtain an empirical correlation for correcting the deviations of both these efficiencies.A new approach proposed in present study is to replace the two maps of combustion and turbine efficiencies by experimentally measured high pressure and low pressure shaft speed curves,which can be used as the known conditions for differential equations describing transient operation of twin spool turbojet engines.Both Euler′s method and Newton-Rapson′s iteration are used in calculation discretizing for and solving the differential equations.Based on the above mentioned approach,a transient operation of a twin spool turbojet engine during pulsatory supply of fuel has been numerically simulated.The numerical results are in good agreement with those experimental measurements.