Cascaded utilization is the most promising solution for the comprehensive recovery of LNG cold energy across the entire temperature range. In this article, the author proposed a cascaded LNG cold energy utilization system, which includes cryogenic air separation (CAS), organic Rankine cycle (ORC), graded cold storage (GCS), and direct expansion (DE). A thermodynamic model of the proposed system was established. Based on this, with the objective of maximizing exergy efficiency, a global optimization of the proposed system was carried out using the particle swarm optimization algorithm. The results indicated that the optimized system could achieve efficient utilization of LNG cold energy. The total cold energy provided by LNG is 860.90 kW, of which 708.07 kW is utilized by the process, accounting for 82.24% of the total cold energy. Within different temperature ranges, the CAS, ORC, and GCS subsystems respectively utilize 21.23%, 21.34%, and 30.87% of the LNG cold energy. The total exergy loss of the system is 385.67 kW, with an exergy efficiency of 79.55%. Moreover, the total simulated power generation of the CAS-ORC-GCS-DE-LNG system is 120.92 kW, and the three expansion devices, the expander, Turbine 1 and Turbine 2, generate 12.85 kW, 29.12 kW, and 78.95 kW each. Additionally, the exergy loss of the cryogenic air separation module is 229.25 kW, accounting for 59.44% of the total exergy loss of the proposed system. Therefore, optimizing the cryogenic air separation module is a feasible approach to improving the thermodynamic performance of the proposed system.