Abstract: A loose-proof connector includes a screwing sleeve and a connecting body. The screwing sleeve is an annular body and has a circular through hole. The inner wall of the circular through hole is provided with a plurality of recessed arcs that are arranged circumferentially. The connecting body is inserted into the circular through hole of the screwing sleeve. An annular band of the connecting body is provided with protruding arcs to correspond to each recessed arc. The protruding arcs oppose to the any one of the recessed arcs and thus are adjacent thereto. Via this arrangement, the protruding arcs can bounce between any two adjacent recessed arcs, thereby generating a locking effect, and thus the loose-proof effect can be surely achieved.