The utility model relates to a heavy hydrocarbon recovery system for LNG-FPSO, its characterized in that: it includes a cold box, a precooling system and a heavy hydrocarbon piece-rate system, six pipelines that are used for the heat transfer have been set up in the cold box, the precooling system includes low pressure separator, the first compressor, first blender, second compressor, second blender, third compressor, first cooler, first choke valve, high-pressure separator, first shunt, second choke valve, middling pressure separator, second shunt and third choke valve. The heavy hydrocarbon piece-rate system includes vapour and liquid separator, natural gas expander, deethanizer, fourth choke valve, debutanizing tower, second cooler, the 5th choke valve, NGL storage tank, the 6th choke valve, the 7th choke valve, LPG storage tank. The utility model discloses a precooling system and heavy hydrocarbon piece-rate system internal plant are compact and simple, the installation just is convenient for less to the flow valve member, very easily are applied to the operation on the sea.