Offshore platform lifting device

An offshore platform lifting device for lifting operations at sea after sailed to a certain position of a sea surface, comprising:

• an upper deck;
• a plurality of upright columns, connected to the upper deck and supported on a seabed;
• a rail seat, disposed on the upper deck, the rail seat having a curved rail, two ends of the curved rail being provided with retaining walls;
• the upper deck having a center position relative to the curved rail, the center position being provided with a fixed pulley mechanism;
• a base, disposed on the curved rail, the base having a pushing device disposed on the upper deck for driving the base to slide along the curved rail;
• two davit arms, each having a first end and a second end, the second ends of the two davit arms being pivotally connected to the base and arranged side by side, the first end being provided with a first pulley and a second pulley;
• two first winches, disposed on the upper deck, the two first winches each having a first cable passing through the first pulley of a corresponding one of the two davit arms and connected to the fixed pulley mechanism, wherein when the two first winches each wind and unwind the first cable, the two davit arms are pivoted up and down with the second end as an axis;
• two second winches, disposed on the upper deck, the two second winches each having a second cable passing through the second pulley of a corresponding one of the two davit arms, a hook being disposed at a distal end of the second cable.