Taiwan is the major country of importing LNG. In this paper discussed LNG cold energy recovery used in cold storage warehouse and other energy conservation systems. In the cold storage warehouse systems that showed the less temperature of cold storage warehouse the more exergy efficiency and the best exergy efficiency is 30%. Base on thermoeconomic analysis there was the optimal operation temperature at -70¢J. In the purifier nitrogen system (PNS), the investigation indicated the best efficient operating temperature at -150¢J. But with economic analysis the optimal design temperature of this PNS was -130¢J. And the last energy conservation system was the running power plane. In this research studied the power planes used LNG cold energy as inlet air-cooling systems. According to the investigation that showed the systems increased power output up to 14.4¢H in the 4.5¢J of inlet air cooling temperature. And these systems also improved the heat rate of power planes about 0.98%. The conclusions presented that the potentialities of LNG cold energy are huge, and with proper engineering and economic analysis could make these energy conservation systems more feasible.