The invention provides a sulfur hexafluoride (SF6) micro water tester joint fixing device and a using method thereof. A tester joint flange and an inflation joint flange are pressed by employing a method for increasing a flange (namely a support), and the design of matching a hook and a handle is used, so that the inflation joint flange can be hooked by the hook, and the tester joint flange and the inflation joint flange are tightly connected. According to the SF6 micro water tester joint fixing device and the using method thereof, the original step of clamping and connecting the flanges by using a wrench or a fastener is simplified, the operation of pressing and connecting the joint can be easily finished without excessive manual labor, the testing time is shortened, and the working risk is reduced.