The invention provides a secondary battery and a pole piece thereof. The pole piece comprises a current collector, an active material layer and a first protective layer. The current collector comprises an insulating layer and a conductive layer arranged on the surface of the insulating layer, the conductive layer is provided with a main body portion and a protruding portion connected with the mainbody portion, and the surface of the main body portion away from the insulating layer is covered by the active material layer, and the surface of the protruding portion away from the insulating layeris not covered by the active material layer. The first protective layer is arranged on one side of the protruding portion away from the insulating layer. The pole piece further comprises a conductivestructure, the conductive structure comprises a connecting portion and a first extending portion, the connecting portion is fixed to the protruding portion, the first extending portion is connected to the connecting portion and exceeds one end of the protruding portion away from the main body portion; and along the height direction, the first protective layer is located one side of the connectingportion close to the active material layer. The secondary battery provided by the invention comprises the above pole piece.