One end of a kind of safe needle cover of injection needle tube, the injection needle tube forms a convex pipe, and the convex Guan Youyi first segment and a second segment are formed, and the shape system of the second segment is in a polygon, which includes a fitting portion, a movable bending part and a cover. The fitting portion forms one of what safe needle cover end, forms a positioning hole in the fitting portion, and the shape system of the location hole is in a polygon, the corresponding cooperation second segment of the location hole, and the second segment is across the location hole, the fitting portion fitting second segment. Between the position what of the activity bending part fitting portion and the cover. By the corresponding shape for cooperating the second segment of the shape of the location hole in the fitting portion, the safe needle cover can be prevented with respect to what, and the injection needle tube twists, and then the cover of the safe needle cover is avoided to separate with the syringe needle.一種注射針筒之安全針蓋，該注射針筒之一端形成一凸管，該凸管由一第一段及一第二段所組成，該第二段之形狀係呈一多邊形，該安全針蓋包含一套合部、一活動彎折部及一蓋部。該套合部形成於該安全針蓋之一端，該套合部內形成一定位孔，該定位孔之形狀係呈一多邊形，該定位孔相對應配合該第二段，該第二段穿過該定位孔，該套合部套合該第二段。該活動彎折部之位於該套合部與該蓋部之間。藉由，該套合部之定位孔之形狀相對應配合該第二段之形狀，能夠防止該安全針蓋相對於該注射針筒發生扭轉，進而避免該安全針蓋之蓋部與該針頭分離。
