External safety sleeve of injector

The utility model relates to an external safety sleeve of injector, comprising an inner tube and an outer tube set outside the inner tube. One end of the outer tube is inwardly and convexly provided with a plurality of bumps. One end of the inner tube form s a built-up construction, which is provided with a flat plate. The two ends of the flat plate extend upwardly and form a protecting block, the longitudinal profile of which forms a reversing L shape. The cavity of the protecting block forms a containing chamber, in one end of which a barrier chip is formed. The gripping section of the injector is rotating and fastened to in the built-up structure, as to make the injector and the inner tube combined. After the injector is used, the outer tube cab is pulled-down and fastened to the other end of the inner tube, covering the syringe needle of the injector. Thus the external safety sleeve of injector is convenient for assembling, and adaptive to different injectors, it can also prevent the accident of hurting people by the syringe needle.