The invention relates to a fabrication method of a soft pack battery. The fabrication method comprises the following steps of 1) pasting two side thickness surfaces of a lamination battery cell with adhesive tapes; 2) performing top sealing on the top of the battery cell with a tab by an aluminum plastic film, performing side sealing on one of the side thickness surfaces of the battery cell, allowing the other side thickness surface of the battery cell to face an air bag mouth packaged by the aluminum plastic film, and locally packaging the aluminum plastic film at a downstream of an adhesivetape pasting position on the other side thickness surface along an air exhaust direction; and 3) performing liquid injection, primary sealing, formation, air pumping and secondary sealing after localpackage, thereby obtaining the soft pack battery. According to the fabrication method of the soft pack battery, provided by the invention, local package is performed on the aluminum plastic film aftertop sealing and side sealing of the battery cell, so that the adhesive tape is prevented from being directly sucked during the subsequent air pumping process, the stress to the adhesive tape during the air pumping process is reduced, and the pasting failure of the adhesive tape is prevented.