The invention provides a transport system, a crane and a moon pool trolley for a drilling ship. The crane is used for hoisting a blowout preventer or a Christmas tree, and the crane comprises a main beam structure and two main winches, wherein a rail is arranged on the main beam structure in the length direction of the main beam structure; and the two main winches can move along the rail to adjustthe distance between the two main winches in the length direction of the main beam structure. Through the arrangement of the transport system, the crane and the moon pool trolley for the drilling ship, the transport system can be shared by the blowout preventer and the Christmas tree, and thus the space occupied on the ship is reduced, and the deck load is reduced.