The utility model discloses a fairlead for positioning a large-sized suspension box-cofferdam, which comprises a steering device. The steering device is the transitional device of a fixed seat and a connecting plate; one end of the steering device is connected with the fixed seat through a transverse pin shaft, and the other end is connected with one end of the connecting plate through a vertical pin shaft; a traction box which is used for the passing of fairlead traction ropes and is formed by a plurality of sets of pin shafts is formed at the other end of the connecting plate; and the pin shafts and a steel sleeve are the bearings of the traction box at the end head of the connecting plate. The utility model adopts the following positioning method: the fixed seat is arranged on the outer wall of the suspension box-cofferdam; the fixed seat, the steering device and the connecting plate are connected through pin shafts to form an integral flexibly rotatable system to be pulled; and after the fairlead is mounted, the traction ropes are mounted in place through the pin shaft traction box of the fairlead, the suspension box-cofferdam is adjusted to an appointed positioning site to realize accurate positioning. The fairlead with the advantages of simple structure, convenient operation, definite stress and low cost can be used for accurate overwater and land positioning of other large-sized equipment with steel structures, and has great popularization value.