At present, there are two ways to detect abnormal sound of bearings. One is noise detection based on acoustics and the other is vibration detection. (1) Noise detection method is a direct measurement method of abnormal sound, which uses high-quality microphones to extract bearing sound pressure signals at a certain distance and direction under the muffled environment of basic noise less than 20dB, and extracts abnormal sound components through certain analysis methods. (2) Vibration detection method is an indirect detection method of abnormal sound, which can be divided into qualitative detection method and quantitative parameter detection method. Among them, qualitative detection method is divided into monitoring abnormal sound method and observation vibration waveform method. Quantitative parameter detection method refers to using the measured parameter values related to abnormal sound in the vibration signal of the bearing under test, such as vibration peak value and wave peak factor to evaluate the abnormal sound of the bearing. (three), measuring instrument bearing abnormal sound measurement of bearing abnormal sound measurement instruments are many