As an important part of mechanical equipment, gear box has large transmission torque, fixed transmission ratio and structure .Compact and other advantages, widely used in the transmission of power and change of speed of the machine. The gear box system is mainly driven by gears. Shaft, bearing and box composition, gear box long time operation may lead to the gear and bearing centralized or distributed failure. Shaft bending can also lead to a series of subsequent failures of gears and bearings. According to the statistics, the gearbox is numerous. One of the parts of mechanical equipment that has a high frequency of failure. Therefore, it is important to study the fault diagnosis technology of gearbox. Significance, not only can shorten the maintenance time and reduce the maintenance cost, but also can improve the accuracy of diagnosis and maintenance quality. Create considerable economic benefits.