According to the analysis on the vibration data of gear and bearing, which are collected during they failed on IGB and TGB bench test of helicopter, the vibration characteristic of the failures are concluded in each phase such as occurrence, extending and alarm. So the diagnoses technique is searched for judging whether the gear and bearing are failed by monitoring the vibration data. This diagnoses technique is substantiated during the following test. The test demonstrates that this method can monitor the failure in advance comparing with the traditional method by chip detector. It can avoid the failure extending, decrease the damage on the test part effectively and ensure the safety of the test. This diagnoses technique can be applied widely for the test of gearbox.