The invention discloses a pumping unit polished rod centering connecting device for connecting a well head tee pipe of an oil field pumping well with a plurality of packing boxes, consisting of a well head tee junction cavity, a translational movable ball seat, a movable ball joint connector, a nylon lining and a ball joint press cap , wherein, the translational movable ball seat is arranged inside the well head tee junction cavity; the movable ball joint connector is arranged inside the transitional movable ball seat; the nylon lining is sleeved inside the movable ball joint connector; the ball joint press cap is in threaded connection with the well head tee junction cavity. The invention replaces the prior inflexible connection of collar clamps and can butt joint with various packing boxes; the structure is simple, convenient and compact, and the device has offset and centering functions under the effect of the translational ball seat and a ball joint, thereby a polished rod is made to be automatically centered. Therefore, the invention solves the environmental pollution problem due to eccentric wear and oil leakage of packings, and has the advantages of reduction of personnel labor intensity, reduction of material consumption and improvement of management level.