The invention provides a nitrogen sealing device for a lower tank body of a residue tank. A nitrogen package is arranged on the side wall of the lower tank body of the residue tank and communicates with a nitrogen inlet pipe penetrating through the side wall of the lower tank body of the residue tank; multiple evenly-distributed exhaust vents are formed in the lower portion of the nitrogen package; the two ends of the nitrogen package communicate with the nitrogen inlet pipe; the lower portion of the nitrogen package inclines to the inner side of the lower tank body of the residue tank, and the exhaust vents correspondingly incline. According to the nitrogen sealing device for the lower tank body of the residue tank, the arranged nitrogen package forms a nitrogen curtain on the inner surface of the lower tank body of the residue tank, the working condition of the residue tank cannot be affected, and safe operation of a glass tape in the residue tank is guaranteed; due to the fact that adjustment is easy and operation is stable, the surface defects of ultra-thin glass can be effectively reduced, and the production quality is improved.