The present disclosure illustrates a fixing device comprising a sleeve which has a through hole inside and has grooves recessed on an outer surface thereof, and is placed inside receiving space of an outer casting tube, and the receiving space being formed with longitudinal protrusion rib disposed on an inside wall thereof and slidable in the grooves, and a head part is disposed inside the receiving space and has a mounting; a resilient component is abutted between the head part and the sleeve; a fastener fixed on the head part and having a riveting part mounted in the mounting hole, and a rod extended from a bottom thereof and inserted through the through hole, and having longitudinal sections and arc surfaces and the rod having a stop part outwardly protruded on a bottom side thereof, and having a guiding incline formed at top thereof.