The utility model relates to an oil development well head water -tight equipment, in particular to polished rod sealer of oil pump. Including the one -level seal, prevent spouting nipple joint, second grade seal, the one -level seal, prevent spouting nipple joint, second grade seal and be the concentric tubulose body of suit on the polished rod, threaded connection in proper order, the internal diameter of preventing spouting the nipple joint is lighter than the internal diameter of one -level seal and second grade seal, installs the packing in the cavity of one -level seal, second grade seal respectively, prevent spouting and install the preventer on the pipe wall of nipple joint, the preventer include with the cavity of the ascending nozzle stub of slope of preventing spouting nipple joint cavity intercommunication and nozzle stub in end cap, spring, ball seat and the ball sealer installed in proper order. The utility model discloses a sealed, lubricated and set upright or straight to the doublestage of polished rod, still realized that the polished rod takes off the back to the automatic shutoff in the twinkling of an eye of sealed ware, simple safety absolutely simultaneously.