The variable cycle engine model is established and the variable geometry low pressure turbine characteristics are modified. The results show that the reduced flow rate at the inlet of the low pressure turbine increases with the increase of the angle of the low pressure turbine deflector. With the increase of guide vane opening， the expansion ratio of high pressure （HP） turbine， the power of HP shaft， and the pressure ratio of high pressure compressor（HPC） to core driven fan stage（CDFS） increase. The specific thrust reaches its maximum when the turbine guide vane angle is 0° in double bypass mode and the turbine angle is -1° in single bypass mode，respectively.