The invention discloses a fault diagnosis method. A bearing impact energy value and a spectrum are acquired from a detection end; the belonging interval is judged according to the impact energy value,if the impact energy value is located in a supervision enhancement interval, whether fault features happen to the spectrum is judged, if the fault features appear, whether a fault frequency exists iscalculated according to the spectrum, and if the fault frequency exists, the bearing is disintegrated; if the impact energy value is located in a device fault interval, whether temperature abnormality, noise abnormality, white noise and a high-frequency component appear is judged, if any of the above features appears, lubrication is carried out, if the temperature abnormality, the noise abnormality, the white noise and the high-frequency component do not disappear completely after the lubrication, whether a fault frequency exists is judged, and if the fault frequency exists, the bearing is disintegrated. As interval processing is carried out on the impact energy, various fault features appearing in the spectrum and the fault frequency are combined in different energy intervals to judge the bearing, the state of the bearing can be accurately judged, and the bearing can be disintegrated in a corresponding state.