The utility model discloses a screw thread protection device belongs to oil machinery. Include: built -up member, mounting and bearing regulating part, built -up member include the semi -cylindrical form sleeve and with semi -cylindrical form sleeve fixed connection's semicircle ring flange, be provided with the curved surface notch on the semicircle ring flange, first built -up member and second built -up member are all detained and are put on the rising nipple joint during use, and the mounting is with first built -up member and second built -up member fixed connection, and the semi -cylindrical form sleeve of first built -up member forms cylindric sleeve with the semi -cylindrical form sleeve of second built -up member, and the semicircle ring flange of first built -up member forms cylindric ring flange with the semicircle ring flange of second built -up member, and cylindric sleeve butt connects on end flange, the bearing regulating part set up on cylindric ring flange and the butt on the sleeve pipe blind plate. The utility model provides a screw thread easy problem of damaging, reached the effect of avoiding the screw thread to damage. The utility model is used for the protection of screw thread.