Due to the convenience of low temperature liquid storage and transportation and simple operation, the liquid air separation plant liquefies the excess oxygen and nitrogen released at ordinary times into liquid oxygen and liquid nitrogen, which can be provided to nearby units or individuals in need or used for peak shaving, which can greatly improve the utilization rate of oxygen and nitrogen, and has considerable economic benefits. A liquid air separation plant is composed of a set of full distillation gas air separation equipment and a set of nitrogen circulation liquefaction equipment, which can produce liquid oxygen and liquid nitrogen products according to the actual requirements of users, and extract high-purity nitrogen and high-purity oxygen products at the same time.