A battery pack mounting module for a vehicle is provided. The battery pack mounting module includes a seating flange fixed to a lower portion of a side sill, a fixing flange fixed to a battery pack panel under a battery pack, a mounting arm positioned between the seating flange and the fixing flange, and a plastic hinge A and a plastic hinge B formed at both sides of the mounting arm, wherein when a collision occurs on a side surface of the vehicle, the battery pack is configured to perform a downward movement by deformation of the plastic hinge A and the plastic hinge B to induce an avoidance behavior trajectory by a rotation motion of the mounting arm to avoid a collision between the battery pack and the side sill.