Rotary coupling for crown block lifting hook

The utility model discloses a rotary coupling for a crown block lifting hook, the rotary coupling for the crown block lifting hook comprises a coupling body, a flange, an insulating washer and an insulating sleeve, the coupling body is provided with a shaft hole, a plurality of first bolt holes and a plurality of positioning pin holes; the flange is provided with a plurality of second bolt holes and a plurality of positioning pins, the second bolt holes are matched with the first bolt holes respectively, and the positioning pins are matched with the positioning pin holes respectively. The positioning pin holes in the coupling body are matched with the positioning pins on the flange, so that the stress of each part of the coupling under the heavy load condition is effectively reduced, the stress from the output end to the moving end is uniform in the torque transmission process, the transmission efficiency and the connection strength are higher, the shearing stress generated by inertia when a lifting hook lift