Full liquid air separation plant requires more cooling capacity than air separation plant. According to different production requirements, cycle compressor refrigeration, high and low temperature pressurized booster expansion refrigeration, low temperature pre-cooling unit and other processes are adopted to reduce energy consumption effectively. The related control system adopts DCS computer control system or PLC control system, and part of the on-site indication, so that the whole set of equipment can achieve the purpose of simple operation, stability and reliability. In order to reduce energy consumption, it is also possible to recover vaporization cold energy such as LNG/liquid nitrogen/liquid oxygen/liquid argon to make liquid air separation plant or liquefaction process.