The invention relates to the field of oil supplement of high-voltage sleeve pipes, in particular to a method and device for supplementing oil to an electrified transformer sleeve pipe. Electrified oil supplement is carried out on the top of a primary sleeve pipe and a secondary sleeve pipe of a transformer with the voltage level higher than 66kV by adopting an equipotential operation method. The method comprises the following specific operating steps that (1) the phase position of the sleeve pipe must be checked before the oil supplement to confirm the consistence with the emergency repair instructions send out by production scheduling, and the facts that the quality of oil in an oil supplementing barrel is qualified and the type of the oil in the oil supplementing barrel is identical with that of the oil inside the sleeve pipe are confirmed; (2) an insulation herringbone ladder is assembled on the ground; (3) after a potential electrician climbs to an operation site at the upper end of the sleeve pipe of the transformer along the herringbone ladder, a safety belt and a shielding potential equalizing wire are hung, sealing screws of the sleeve pipe are unfastened, and an oil filling pipe of the oil supplementing device is inserted into a sealing hole of the sleeve pipe. Compared with the prior art, the method and device for supplementing the oil to the electrified transformer sleeve pipe have the advantages that an equipotential mode of electrified operation is adopted, the blank in the technical aspect of the electrified oil supplement of the transformer sleeve pipes is filled, and good economic benefit and wide application prospects are achieved.