As the core component of automotive rear axle,the automotive main reducer undertake the function of slowdown and increase driving moment,its quality directly affects the safety and comfort of automotive.Taking the order analysis method as the core,the vibration signal analysis method of the automotive rear axle main reducer is designed based on the virtual instrument technology,the signal is collected by the data acquisition card and transmitted to the computer through the USB bus.The time point of vibration signal resampling is obtained through the processing of rotational speed signal,the order spectrum of the vibration signal is obtained by the frequency spectrum analysis of the vibration signal resampling,and the order spectrum is compared with the original vibration signal frequency spectrum,the clear frequency component is obtained,the problem of frequency alias produced by the speed fluctuation is solved.