Abstract: A safety syringe capable of avoiding retraction of a needle during sucking medicine/injection, including: a barrel; a needle holder inserted in the top end of the barrel for holding the needle; a first leakproof body fitted on the bottom end of the needle holder, a circumference of the first leakproof body tightly attaching to the inner wall of the top end of the barrel; and a plunger slidably fitted in the barrel, the top end of the plunger being formed with a latch head section for correspondingly latching with the needle holder. A circumference of the bottom end of the needle holder is formed with multiple flange sections. An annular fixing groove is formed on top end of the barrel. The flange sections of the needle holder are inlaid in the annular fixing groove, to prevent the needle be retreated into the barrel during sucking or injection.