Abstract: A fixing structure of a dental handpiece has a transmission assembly for connecting a handpiece head, a positioning sleeve sleeved onto the transmission assembly and having a positioning member thereon, and a casing composed of a front casing and a rear casing. The front casing is sleeved onto the positioning sleeve. The rear casing is detachably connected to one end of the front casing. The front casing is provided with a push member. The push member is inserted inwardly to lean against the positioning member for the positioning member to be tightly pressed against an outer circumferential surface of the transmission assembly so that the front casing, the positioning sleeve and the transmission assembly are fixed and connected together.