A steady and transient component-level mathematical model of a double bypass variable cycle engine (DBVCE) was constructed considering the effects of variable inlet guide vane and variable turbine nozzle area on component characteristics of compressor and turbine.Besides,the effects of the mode selector valve area on deputy bypass inlet air flow were also considered during the modeling process of DBVCE;two typical operation modes such as steady state and mode switching transient process were simulated.Results show that as the mode selector valve closes down,the surge margin of front fan block decreases obviously.When working in double bypass mode,the specific fuel consumption of DBVCE is lower,which is fit for subsonic cruise flight;otherwise,the specific thrust is higher in single bypass mode,which is fit for supersonic cruise flight.