The utility model provides a sulfur hexafluoride density calibration device for relay, including inflate the mechanism, move stopper drive handle, drive mechanism, two air ducts and sulfur hexafluoride check gauge, inflating the mechanism and including the inflator pump, move stopper and mounting bracket, first ring flange is installed to inflator pump second end, the connecting pipe is all installed at the both ends of air duct, and the connecting pipe is inside to be equipped with the collar, and movable installation has sealed dish on the collar, and the connecting pipe is kept away from one side of air duct and is installed the second ring flange, the sulfur hexafluoride check gauge has two air guide hole, and the sulfur hexafluoride check gauge corresponds air guide hole's position and all installs the third ring flange, and movable installation has first supporting to lean on the post on the third ring flange, movable installation has the second to support by the post on the first ring flange. The utility model discloses convenient to use has practiced thrift the manpower to the influence to the environment has been reduced.