The present invention provides a safety sheath for hypodermic syringe needle comprising a proximal mounting ring, a distal mounting ring and a shielding sheath. The shielding sheath includes two symmetrical slits, two symmetrical semicircular aprons and an inward annular fillet, which is bisected into two symmetrical curved segments with crescent thickness, namely marginal thickness is less than central thickness. During sleeving the shielding sheath over the distal mounting ring and proximal mounting ring, both symmetrical semicircular aprons are outwardly hauled by outwards forces such that the bore profile of the inward annular fillet is dilated into circular shape, which will not only facilitate subsequent sleeving process without difficulty but also enhance the tightness for the latch of the shielding sheath with the distal mounting ring in locked manner without any possibility of mutually slipping displacement so that medical personnel in handling can prevent from accidental pricks by hypodermic needle.
