Using the air compressor to produce gas, the generated gas is stored in the air tank and then driven to the drying freezer via an air tank for drying treatment. The moisture and oil are separated by using a precision filter. Part of the gas is used for production, and part of it is diverted into the nitrogen generator. The nitrogen produced is collected in the storage tank, and is compressed and stored to the high pressure cylinders by using a nitrogen high pressure compressor. When the nitrogen-supported filling is required in the injection formation, the nitrogen is blown into the production mold through the air needles of the pressure distributor and mold to achieve hollow effect.