The safety syringe includes a barrel having a clamping slot, a large sealing ring and a zero line； a plunger having a pull pawl and an annular convex clamping disc, an avoiding seams； a rubber plug； a needle connector having annular clamping pawls, an inner sealing ring and a pullback ring； and a locking body made of a polymer material with elasticity and having a sealing disc, a sealing ring, a clamping ring and a checking ring. The sealing disc, large sealing ring, sealing ring and inner sealing ring are engaged to constitute a sealing structure. When the clamping ring meshed with the pull pawl is dragged to retract inwards, the sealing ring and pullback ring are engaged to pull the needle connector to retract, and the checking ring is plugged into the inner cavity of the clamping pawls to fix the clamping pawls in the clamping slot.
