The invention discloses a nitrogen recompression system which comprises a waste gas burning pipeline. The nitrogen recompression system is characterized in that a decompression valve, a pressure relay and a nitrogen input pipeline provided with a solenoid valve are arranged on an anterior chamber of a thermal treatment furnace; and the nitrogen input pipeline is connected with the decompression valve through the solenoid valve, and also connected with the anterior chamber through the solenoid valve. The invention has the benefits that the nitrogen recompression system can effectively solve the problems of the backflow of oxygen-containing air and the change of gas pressure in the anterior chamber, and enhance the reliability and the security of equipment.