The present invention provides medical syringe for preventing needle-stick injury, wherein an inner diameter of a middle part of an elastic disengaging ring is larger than an inner diameter of a front part and an inner diameter of a rear part. The elastic disengaging ring is located between a distal wall of a syringe barrel and a needle. When the middle part of the elastic disengaging ring plugged onto the conical fitting of the syringe barrel is radially pinched flat, the proximal end of the elastically deformed elastic disengaging ring leans against the distal wall of the syringe barrel, and the front end of the elastically deformed elastic disengaging ring leans against the proximal end of the needle and pushes the needle to move forward, so that the needle is disengaged from the conical fitting of the syringe barrel.
