Abstract: Based on a general gas turbine performance simulation software,a double bypass VCE(variable cycle engine) performance simulation software was developed with introduction of selector valve,forward VABI(variable area bypass injector) and rear VABI and core bypass duct modules.The cycle operating parameters of VCE were given,such as low pressure turbine nozzle area,compressor inlet guide vane angle,fan inlet guide vane angle and core-driven fan stage inlet guide vane angle.A double bypass VCE characteristics were calculated and analyzed with altitude velocity and throttling in this paper.Compared with single bypass mode,the specific thrust and specific fuel consumption(SFC) of double bypass mode were low.The total bypass ratio increased and the SFC decreased with the decline of rotate speed.Under a complicated condition,it is necessary to match the engine with appropriate variable parameters.