A general method for the cycle power balance calculation of the liquid rocket engine is proposed in this paper. The components of the engine system are calculated iteratively in a predetermined sequence, and a modified Newton method is used to find the unknown variables of the system. This method is universal for the analysis of liquid rocket engine cycles. The program based on the method is achicved by the object-oriented programming. The stage combustion cycle using the liquid oxygen and methane as propellant is calculated with the program, and the calculation results are also given.