The invention relates to a lightning arrester structure of a transformer and a lightning arresting method, belonging to the technical field of the transformer. The technical scheme is as follows: for the transformer using the oil charge outlet, the middle part of a lead for connecting an oil insulating sleeve pipe with a cable terminal in the outer shell of an oil charging device is added with a T-shaped lead connector, thereby generating a lead branch connected to an SF6 lightning arrester; the lead branch direction is perpendicular to the ground and connected with an oil-SF6 sleeve pipe; thus the outer shell of the transformer oil filling device is integrally formed to be an E-shaped structure; the oil-SF6 sleeve pipe is connected with the SF6 lightning arrester, thus the ordinary lightning arrester can play the role of protecting the transformer while the metal outer shell can play the role of mechanically supporting the entire charging oil outgoing line transformer; the invention can protect the oil outlet transformer by using the ordinary SF6 lightning arrester, and improve the technical economy of the protecting scheme of the lightning arrester while enhances the mechanical stability of the oil outlet structure of the transformer.