The utility model provides a cold energy cascade utilization system of LNG transport ship, including LNG force (forcing) pump, compressor, system nitrogen circulation system, two -stage rankine cyclepower generation system, seawater desalination circulation system, low temperature cold storage house circulation system, high temperature freezer circulation system, ship air conditioning system andsteam turbine exhaust steam heating device. Liquid LNG is through LNG force (forcing) pump pressurization back cooling in system nitrogen circulation system and two -stage rankine cycle power generation system, later mixes cooling in seawater desalination circulation system, low temperature cold storage house circulation system, high temperature freezer circulation system, air conditioner circulation system in proper order again, (25 DEG C ) entering boiler combustion after the steam turbine exhaust steam is heated with BOG after the compressor compression. Wherein, second level rankine cyclesends out electric steaming and sends out the heating of ware adoption exhaust gas of boiler. The utility model discloses to the characteristics of LNG transport ship cold energy, adopt cascade utilization's mode, make full use of LNG transport ship used heat, improved LNG transport ship cold energy and cold (img file='dest_path_DSB0000163865780000011. TIF'wi='52'he='54''s /) comprehensive utilization ratio.