Abstract: Causes of accidents, in which operators were hit and injured by pipe tongs during oil-well repair, were analyzed. The structure and working principle of a new type pneumatic chuck used in oil-well repair were introduced. With this kind of pneumatic chuck, operators could fasten or loose the oil pipe by operating the dynamic control valve in control cab. Since operators need not to directly touch the pipe tongs any more, such accidents could be avoided so as to gain obvious economic as well as social benefits. Automatic operation could be achieved when these pneumatic chucks are used simultaneously with the automatic safe operation device of hydraulic clippers.