The invention is an offshore aquaculture facility based on the modification of a bulk cargo ship. It is achieved by converting a bulk cargo ship into a floating offshore facility at sea, with a number of cultivation tanks located below the deck, a movable hoisting system on the deck, a water-changing system in the cultivation tanks, and there are sealed void spaces between the shell plate of the offshore farming facility and the outer wall of the cultivation tank to provide buoyance for the facility. There are auxiliary cultivation compartments which are equipped with a water monitoring system, and equipment compartments on the deck. And a mooring device is installed in the bow of the facility. The benefits of the invention is that it is suitable for salmon cultivation in the northern part of the Yellow Sea or other waters and it can be up to 100-200 nautical miles offshore. Supplemented by specially designed mooring devices, it can resist the strongest typhoon that may appear in the area, ensuring that it can operate in a fixed sea area for 10 consecutive years under any sea condition.
