Disclosed are a secondary battery, a battery module and an electric vehicle. The battery module includes a plurality of secondary batteries arranged in sequence. The secondary battery includes an electrode assembly, a housing and a top cover assembly. The electrode assembly is accommodated in an accommodating chamber of the housing. The electrode assembly includes a plurality of electrode units, the plurality of electrode units being stacked in an axial direction of the accommodating chamber. The top cover assembly includes a top cover plate and an insulating member arranged on an inner side of the top cover plate, the top cover plate being connected to the housing, the insulating member being located on a side of the electrode assembly in the axial direction. A first buffer gap is provided between the insulating member and the top cover plate.