Back-up wrench special for wellhead flange screws

The utility model belongs to the technical field of oil field oil extraction operation auxiliary tools. The utility model relates to a wrench, in particular to a back-up wrench special for wellhead flange screws. The wrench is characterized by comprising an active wrench and an ejector rod type back-up wrench matched with the active wrench for use, the active wrench comprises an adjustable anti-bouncing device and a socket wrench I arranged below the adjustable anti-bouncing device, and the ejector rod type back-up wrench comprises a socket wrench II and a telescopic ejector rod arranged belowthe socket wrench II. The tool is simple in structure, convenient to operate, good in safety, wide in application range and capable of being independently operated by a single person, the dangerous behavior that a wellhead flange screw needs to be assembled and disassembled through cooperation of other people is eliminated, and the tool can be used for construction of assembling and disassemblingthe wellhead screw in oil