The utility model relates to a high voltage electrical field, and especially relates to a gas insulation switchgear fault arc limiting device and a trigger device thereof. The gas insulation switchgear fault arc limiting device comprises the trigger device. The trigger device comprises a cylinder body and a piston which is assembled in the cylinder body. A push rod is arranged on one end of the piston. A rod cavity is formed at a part, which is located on one side of the piston, of an inner cavity of the cylinder body, wherein the side of the piston is close to the push rod. A rod-free cavity is formed at a part located on the other side of the piston. The rod-free cavity is connected with a gas connection valve. The gas connection valve is in sealing connection with the cylinder body. A constant force limiting mechanism which is in limiting matching with the push rod and can release limiting on the push rod when the piston is under pressure is arranged on one end, which is close to the push rod, of the cylinder body, wherein the pressure magnitude is set by the rod-free cavity. The gas insulation switchgear fault arc limiting device provided by the utility model solves the problems of high cost and long response time of the existing fault arc limiting device.