Abstract: The object-oriented technology is an effective approach in establishing an extendable and reusable simulation platform for aeroengines.The method and process of developing simulation software for aeroengines with Unified Modeling Language (UML) was discussed.The simulation model software was described using case diagram,class diagram,sequence diagram and activity diagram.Aeroengine model classes,solver classes and user interface classes were programmed with C++ language.On the simulation platform,steady state and transient simulation of a twin-spool turbofan engine have been realized.It shows that UML is effective in establishing extendable and flexible simulation software for aeroengines.