Considering the shortages of current modeling methods of gas turbine engine simulation systems, this paper analyzes in detail the process of modeling using object-oriented approach. The class structure suitable to the simulation system was designed. Properties and methods for each component class are increased, the basic class library of the simulation system is completed, and a set of model components are developed which can be re-used in simulation system. With a detailed analysis of the aerothermodynamics of engine components, this paper conducted a further subdivision, induction and abstraction of these components, and finally proposed such a method of class division that chooses the minimum process of aerothermodynamics calculation of gas turbine engine as the basic unit. The model based on the above mentioned method is of good expansibility and flexibility and can be applied to the gas turbine engine performance calculation with different types and complexity. By combining these components logically in the visual window frame, the user can easily complete the simulation model creation and then conduct the related calculations.