Air separation process capable of reducing energy consumption

The invention relates to an air separation process capable of reducing energy consumption. A rectifying tower adopted for air separation comprises a high-pressure lower tower and a low-pressure uppertower. The air separation process is characterized by comprising the following steps that after pretreated air is cooled by a main heat exchanger, the cooled air is fed into the rectifying tower fromthe bottom of the high-pressure lower tower to be rectified, nitrogen and oxygen components are separated out; the low-pressure upper tower is communicated with an external liquid nitrogen storage device, liquid nitrogen in the liquid nitrogen storage device is fed into the low-pressure upper tower from the top of the low-pressure upper tower, an expansion machine is further arranged to be sequentially communicated with the main heat exchanger and the high-pressure lower tower, and part of nitrogen generated at the top of the high-pressure lower tower is pumped out and then is conveyed to theexpansion machine through t