Thread anti-loosening mechanism

The utility model belongs to the field of mechanical installation, and particularly relates to a thread anti-loosening mechanism which comprises an installation base, a pin shaft, a screw rod, an extension spring and a rotating arm. A threaded hole for mounting the screw rod is formed in the mounting seat, and a plurality of small holes are uniformly distributed along the circumferential direction of the threaded hole; the screw rod can be mounted on the mounting seat through the threaded hole; two sides of the upper end of the screw rod are designed into plane structures; one end of the rotating arm is of a double-lug structure, double lugs are rotationally installed on plane structures on the two sides of the upper end of the screw rod, and the rotating arm can rotate around the screw rod. The other end of the rotating arm is further provided with a limiting protrusion capable of being inserted into a small hole in the upper surface of the mounting base. Pin holes are further formed in the plane structures