The invention discloses an LNG power ship fuel cold energy comprehensive utilization method and further discloses a system achieving the LNG power ship fuel cold energy comprehensive utilization method. Firstly, the cold energy of deep cooling LNG fuel is converted into electric energy through Rankine cycle power generation; and secondly, the cold energy of intercooling LNG fuel is recycled by a refrigerant and is applied to each refrigeration demand unit of a power ship grade by grade for cooling, so that the temperature of the liquid low-temperature LNG fuel is raised to a temperature required by power ship air intaking. The LNG power ship fuel cold energy comprehensive utilization method and the system have the advantages that the cold energy of LNG fuel fed to a main engine of a ship is first used in ship power generation, low-temperature cold storage, seawater desalination, high-temperature cold storage, air conditioning and the like grade by grade and then the temperature of theLNG fuel reaches the temperature required by air intaking of the main engine, and the LNG is fed to the main engine for combustion; and the cold energy of the LNG fuel is reasonably utilized grade bygrade, so that the cold energy and cold exergy (imgfile =' DDA 0001765784070000011. TIF 'WI =' 45' he =' 51' /) comprehensive utilization efficiency can be improved, and the operating cost of the shipis reduced. The cold energy of the limited LNG fuel can be reasonably distributed and utilized to a great extent on different types of ships through corresponding adjustment according to refrigeration requirements of the different types of ships and working conditions under different space-time conditions.