Abstract: A generalized gas turbine simulation software must be not only capable of extending to new engine components and configuration,but also able to shift among different simulation algorithms.For this purpose the object-oriented analysis and design method is applied and the Unified Modeling Language (UML) is used.Different computational tasks of simulation are categorized and summarized into a 3-layer generalization:component calculation,gas path calculation,and system state calculation.Based on this generalization,a class framework is proposed and a Node-Connector-Component model is presented and analyzed.New components,gas path algorithms,and numerical integration methods can be extended from the appropriate base classes in the framework. New engine configuration can be realized by connecting nodes in different components.A 3-shaft gas turbine engine's dynamic performance is simulated using an innovative gas path calculation method,the plenum algorithm.The extendability of the model is fully verified.