Abstract: Floating liquefied natural gas production, storage and unloading unit special liquid cargo vessel (FLNG), as a new device for the development of offshore natural gas fields, greatly facilitates the development and utilization of deep-sea gas fields. This paper proposes a new type of cryogenic energy management system for special liquid cargo ships using the FLNG "Prelude" as the depot ship. The system mainly uses liquid air as a medium to store and release energy. Through the combination of liquid air-cooling energy and mixed refrigeration cycle, the process of natural gas liquefaction is realized. While improving the production performance of LNG, the CO₂ liquefaction cycle and power production are integrated, and the output performance of the system is improved through CO₂ liquefaction and surplus cold energy generation. The multi-stage utilization of FLNG ship cold energy is realized, and a new method and a new way are provided for FLNG ship cold energy utilization. The proposed system has better performance than the benchmark model and can achieve cost recovery in 7.04 years. Finally, multi-objective performance optimization is adopted to further increase the exergic efficiency of system exergy to 60.67% and reduce the cost by about 2.3%. The special liquid cargo ship low temperature energy management system features high efficiency, low consumption, stable returns and low carbonization, which can better optimize the offshore LNG supply chain and promote the "carbon peak and carbon neutrality" development of the shipping industry.