The invention discloses a detection method and system for the time-varying vibration contribution of a double-rotor aircraft engine, which are used for detecting the vibration contribution of respective vibration of high and low voltage rotors of the double-rotor aircraft engine to the total vibration of the aircraft engine. The method comprises the following steps: converting a time-varying vibration signal into time frequency; computing the time frequency total energy of the vibration signal and the time frequency energy of vibration signal components which are relevant to the high and low voltage rotors in the vibration signal; and computing the time-varying vibration contribution of the vibration signal components which are relevant to the high and low voltage rotors in the vibration signal. The system is implemented on the basis of the method, is convenient to computing the time-varying vibration contribution, and provides support for online quantitative analysis. By adopting the detection method and system, the relative vibration states of the high and low voltage rotors of the double-rotor aircraft engine can be judged rapidly, so that guidance is provided for vibration over-proof troubleshooting of the aircraft engine.