A needle head structure of a safety syringe includes a protecting cover, a first sleeve, a second sleeve, a syringe holder and a plunger. The first sleeve, second sleeve and syringe holder are structures with mutually latched embedding protrusion and latch portion. The plunger includes a guide channel, and is operated with the syringe holder to reduce a remaining liquid. The first sleeve, second sleeve and syringe holder are latched with one another to fix an end of the syringe holder. After the use of the syringe, a first sleeve is pulled towards a an end to link the second sleeve, so that the first sleeve is latched to an end of the second sleeve, and the other end of the second sleeve is fixed to the syringe holder, so as to provide a convenient operation to users and reduce the risk of being pierced by the needle head structure accidentally.