axial flow fan in use, it is difficult to avoid failure. we just need to find the cause of the failure and deal with it in time. The axial flow fan will inevitably produce small vibration during use. vibration is allowed as long as the vibration amplitude of the cooling fan does not exceed the standard. if the vibration amplitude of the cooling fan increases at the original level, especially beyond the allowable vibration value of the standard, it is abnormal vibration. Any abnormal vibration has the potential to damage the equipment. There are many reasons for abnormal vibration of axial flow fan, such as mechanical reasons, medium fluidity and so on. The mechanical causes of abnormal vibration of cooling fan may be low rotor balance, too close rotor speed to critical speed and so on, which need to be considered and eliminated.