The present invention provides an on-load tap-changer fault detection method and apparatus. The method comprises: acquiring a vibration signal of an on-load tap-changer; performing noise reduction on the vibration signal; decomposing the vibration signal subjected to noise reduction, so as to obtain an IMF component; comparing the component with a set threshold, so as to screen out an effective IMF component; splicing energy entropy of the effective IMF component, and calculating information entropy to obtain effective energy entropy that represents frequency domain complexity of the vibration signal; and determining whether the tap-changer has a fault according to the effective energy entropy. The defect that the fault of OLTC and the specific fault type thereof cannot be accurately detected is overcome, so that a more effective method is provided for real-time monitoring of OLTC and monitoring of other electric devices.