The invention belongs to the technical field of battery module bundling, and provides a special full-automatic steel belt bundling machine for a battery module, and a bundling method thereof. The special full-automatic steel belt bundling machine comprises a belt head pressing device, a steel belt half-biting device, a steel belt pressing and welding device, a belt cutting and belt tail pressing device, a steel belt tensioning device, a steel belt clamping and conveying device and a steel belt guiding device. According to the invention, by arranging the guiding device for introducing a steel belt, the steel belt clamping and conveying device for conveying the steel belt, the steel belt tensioning device for punching two bosses on the two sides of the head of the steel belt and tensioning the steel belt according to the set force, the belt cutting and belt tail pressing device for cutting off the steel belt and pressing the belt tail, the steel belt pressing and welding device for pressing and welding the steel belt overlapping area, the steel belt semi-biting device for fixing the steel belt during steel belt recovery and the belt head pressing device for pressing the boss of the belt head of the steel belt into the clamping groove in a battery module, the steel belt can be firmly bound on the battery module; and the special full-automatic steel belt bundling machine has high working efficiency.