The utility model provides a marine LNG supply of fuel system of no storage tank pressure boost unit relates to boats and ships fuel supply technical field, include: a natural gas storage tank for saving natural gas fuel has liquid outlet and a return -air mouth, the vaporization heating unit, with the liquid outlet with return -air oral siphon way intercommunication for return after vaporizing to some LNG fuel the return -air mouth carries out the pressure boost to natural gas storage tank, natural gas output through the gas vent of self will partially be vaporized after heating supplies the engine use, a plurality of control valves are installed the pipeline of natural gas storage tank with on each pipeline of vaporization heating unit. The problem of adopt prior art fuel gas supply system constitute comparatively complicated, annex, more, the complicated technique of equipment is solved.