The present application relates to a secondary battery head cover assembly, a secondary battery including the same and an assembling method thereof. The secondary battery head cover assembly includes a head cover and an insulation structure, the insulation structure includes a top connection sheet and two naked battery core insulation sheets, an electrode pole is provided on the head cover, and an electrode pole through hole is provided at a position on the top connection sheet corresponding to the electrode pole, the top connection sheet is located below the head cover and is connected to the head cover. The secondary battery includes the secondary battery head cover assembly and the naked battery core, the naked battery core is located below the top connection sheet, and the two naked battery core insulation sheets wrap the side and bottom surfaces of the naked battery core.