Locking screw nut including a first screw nut body, a second screw nut body, a fastening screw and a propelling screw, and capable of effectively solving a problem regarding to a negative value region of male threads

This invention discloses a locking screw nut, which includes a first screw nut body, a second screw nut body, a fastening screw and a propelling screw used for providing an opposite action force. The first screw nut body and the second screw nut body have a same inner diameter. An inner wall of the first screw nut body and an inner wall of the second screw nut body are formed with inner threads having a same specification. A plurality of first installation holes used for allowing the fastening screw to be installed are axially formed on the second screw nut body. There are position limiting holes provided with the same amount as the first installation holes and used for positioning the first installation holes axially formed on the first screw nut body. One end of the fastening screw is allowed to pass the first installation holes so as to be received in the position limiting hole, thereby enabling the first screw nut body and the second screw nut body to be tightly fastened. A plurality of second installatio