Planetary gearbox is widely used in many fields due to its robustness and high power-weight ratio, but implement fault diagnosis on it is a challenge all the time. This paper proposed a new fault diagnosis method of planetary gearbox based on EMD and EDT. Firstly, the vibration data is decomposed into several IMFs by EMD. Then select sensitive IMFs which contain main fault information depend on the correlation coefficients between IMF and fault, normal signal. At the same time, extract energy of the sensitive IMFs as feature parameter. Finally, implement fault diagnosis used EDT. The effectiveness of this new method is validated by gearbox vibration data obtained from test-rig, and the final diagnosis results show that the technique is accurate and reliable. It is helpful in practical application.