The invention relates to a safety vein puncture needle, which consists of a sheath, a needle tube, a needle base, a hose, a spring, a shielding sleeve and a disconnection cut-off clamp, wherein the needle tube is inserted and bonded at the front end of the needle base; the needle base is inserted into a longitudinal groove in an inner cavity of the front section of the shielding sleeve by a side wall ridge and is positioned, so that the direction of a cutting edge of a puncture needle tip is consistent with that of a handle; the shielding sleeve is sleeved outside the needle tube, the needle base and the hose; the spring can be compressed in space of the shielding sleeve and the front end of the needle base; the tail end of the shielding sleeve is bonded with the hose by high-frequency heat seal; the disconnection cut-off clamp is sleeved on the tail section of the shielding sleeve, and is inserted into an opening window of the shielding sleeve; and the wall of the lower section of the shielding sleeve is thickened to form a constricted pipe cavity, so that the side wall ridge at the front end of the needle base can be limited. When the puncture needle is used, a thin bridle of the shielding sleeve can be disconnected only by pinching the disconnection cut-off clamp, so that the shielding sleeve moves forwards under the acting force of the spring to cover the puncture needle completely, and the hose is closed by the cut-off clamp to the risk of needling harm, prevent bloodstain, liquid medicine and body fluid in the hose from overflowing and reduce the propagation of hematogenic diseases.