Abstract: The present invention directs a lithium-ion battery pack which is easy to install comprises an cell and a case packaged outside the cell, wherein the cell is packaged in a side case, a bottom plate is packaged at the bottom of the side case, a top plastic part is fixed at the top of the side case, a plastic part rear cover plate is packaged to an opening portion of the side of the top plastic part, all shores of the top plastic part are inserted into the hole positions of the side case respectively, the bottom edge of the top plastic part is jointed with the edge of the top of the side case, an output interface part and an input interface part are installed at a internal position of a side of the top plastic part, which faces towards the opening portion of the side of the top plastic part, the output interface part and the input interface part are fixed on a patch board in a circuit mode respectively, the patch board is electrically connected to an input circuit and an output circuit of the cell respectively,