The invention provides a battery cover plate assembly, a preparation method of the battery cover plate assembly, a single battery and a battery pack. The battery cover plate assembly comprises cover plates, hollow rivets, an electrode terminal, sealing layers and insulating parts, wherein the sealing layers are arranged between the electrode terminal and the insulating parts; the sealing layers in a fused state can be fused with the insulating parts; and microcellular structures are distributed on the surfaces contacted with the sealing layers, of the electrode terminal. The battery cover plate assembly has the following advantages: the sealing layers are arranged between the electrode terminal and the insulating parts and the electrode terminal is pretreated, thus reducing the influence of deformation, especially shrinkage of polymer insulating parts due to various environmental factors, such as temperature and the like on sealing combination of the electrode terminal and the cover plate, improving the binding force of the inorganic metals and the organic polymers, not only improving the connection firmness of the electrode terminal and the cover plate, but also further enhancing the sealing performance of the cover plate assembly and meeting the development requirements of the current batteries. The invention provides the single battery with more stable performance and the battery pack.