Deepwater heavy-load winch system and using method thereof

The invention provides a deepwater heavy-load winch system and a using method thereof. The system comprises a cable storage winch, a traction winch, a pulley system and a multi-stage hydraulic A frame, wherein the pulley system is hoisted below a cross beam of the multi-stage hydraulic A frame; after extending out of the cable storage winch, a cable is wound around the traction winch and the pulley system and droops from the middle of the multi-stage hydraulic A frame, and the tail end of the cable is connected with a heavy object containing part; along with rotation of a winding drum of the traction winch, on the one hand, lifting and sinking of a heavy object are achieved through winding and unwinding of the cable, and on the other hand, the cable storage winch is matched with rotation of the traction winch to tighten or release the cable; and the cable is a synthetic fiber cable. The scheme that a traditional heavy-load winch system uses a steel cable is broken through, a high-performance synthetic fiber c