The invention provides a preparation method of a non-rectangular lamination battery cell. The preparation method of the non-rectangular lamination battery cell comprises the following steps: preparing k types of lamination battery cell units, wherein in the k types of lamination battery cell units, pole piece elements adopted for the preparation of at least two types of lamination battery cell units are different in shape and/or size; laminating the k types of lamination battery cells according to the preset sequence, thereby obtaining the non-rectangular lamination battery cell. The preparation of the ith (i=1, 2...k) lamination battery unit comprises the substeps of setting a lamination pile, wherein the lamination pile comprises lamination groups, and each lamination group comprises mi pole piece elements same in shape and size, ni is more than or equal to 2, and mi is more than or equal to 2, and gaskets between the pole piece elements of all the lamination groups of the lamination pile and the adjacent lamination groups are sequentially positioned in Z-shaped isolation membranes along the piling direction; and disconnecting the isolation membranes at one end of each gasket, positioned in the isolation membrane so as to obtain the corresponding lamination battery cell unit formed by the pole piece elements in each lamination group and the corresponding isolation membranes.