Abstract: An improved nonlinear mathematical model for the steady state operation of a liquid rocket engine is presented By using this model, the effects of each interfering factor on the parameters of liquid rocket engine are computed and analyzed.The comparative analysis is carried out for the effects of the interfering factors on the engine parameters by using nonlinear model and linear method The results obtained can be used for the ana lysis of rocket engine test results, the reliability analysis and the fault analysis, and also for bringing to light the variation of the engine parameters with various interfering factors.