The large-scale air separation plant consists of an air compression system, a large air pre-cooling system, an ultra-large molecular sieve purification system, an air booster system, a booster turbo expander system, an extra large rectification system, and a heat exchange system. Due to the large size of the supporting unit equipment and the high manufacturing process requirements, the selection of its supporting valves is particularly important. It is directly related to production safety, system regulation performance, output quality and investment costs.