The invention discloses a bag-making production line of cubic plastic bags. The bag-making production line of the cubic plastic bags comprises the steps that plastic is placed on a material roller, the plastic is moved to a side edge adhesive mechanism through a feeding mechanism, upper and lower ironing knives are lowered, the upper and lower layers of the plastic pass through the upper and lowersurfaces of a block iron correspondingly, the upper and lower ironing knives fall to be in contact with the plastic, and a side edge is ironed on the bottom surface of the upper and lower of the plastic; then the plastic continues to move forward and move to a middle seam adhesive mechanism to perform bottom surface middle seam ironing edge, then move to a bottom edge shearing mechanism after ironing, and cutting is carried out according to the size of a preset plastic bag through the bottom edge shear mechanism; and a walking mechanism moves to the front side of the bottom side shear mechanism to wait, an automatic clamp clamps 10 plastic bags to move to a side edge shear mechanism after shearing 10 pieces and move to the side edge shear mechanism to cut side edges. According to the bag-making production line of the cubic plastic bags, the cubic plastic bags are formed at a time, high in degree of automation, the efficiency of bag making is improved, the quality of the plastic bags is ensured, manpower is saved, and the cost is reduced.