The invention discloses a transformer on-load tap-changer automatic measuring device, and relates to the on-load tap-changer testing device technology field. The above mentioned device comprises a PLC programmable logic controller; a vibration sensor, which is disposed on a tap-changer, and is bidirectionally connected with the PLC programmable logic controller, and is used to acquire the vibration signals of the related parts of the tap-changer under the control of the PLC programmable logic controller; an angle sensor, which is disposed on the rotating shaft of the tap-changer, and is bidirectionally connected with the PLC programmable logic controller, and is used to acquire the number of turns of the rotating shaft of the tap-changer under the control of the PLC programmable logic controller; and an on-off detection sensor, which is disposed on the high voltage side of the transformer connected with the tap-changer, and is used to determine the state of the tap-changer by measuring the direct resistance value of the transformer. The device is capable of automatically completing the automatic testing of the starting position, the conduction or the disconnection, and the number of turns of the on-load tap-changer, and has advantages of high testing precision, short testing time, and high testing quality.