The utility model discloses a special hook-headed wrench for maintenance of a stuffing box of a water injection pump, which is applied to maintenance of a stuffing box of a water injection pump of an oilfield. The special hook-headed wrench is characterized in that a cylindrical handle is welded on the outer arc surface at one end of an arc steel plate; the other end of the arc steel plate is provided with a screw hole; an adjustable bolt is fixed in the screw hole at the other end of the arc steel plate and consists of a hexagonal body, a threaded body and a cylindrical body; the hexagonal body is arranged at one end of the threaded body; the cylindrical body is arranged at the other end of the threaded body; and the cylindrical body is arranged on the inner side of the arc steel plate and protrudes out of the inner side face of the arc steel plate. The special hook-headed wrench has the effects of being capable of detaching the stuffing box of the water injection pump easily so as to save labor and shorten maintenance time, and being capable of reducing damage to the stuffing box of the water injection pump and further eliminating an accident that a stress application rod for adjusting the stuffing box is bent and broken.