Abstract: A universal joint with a positioning structure contains: a base including a fitting segment disposed on one end thereof and a receiving groove fixed on another end thereof; a tool set including a driving segment formed on one end thereof and a knob mounted on another end thereof; between the receiving groove and the knob being defined an engaging structure; wherein the base includes a fixing structure, the fixing structure includes at least one pressing member fixed on a wall thereof and a sliding sleeve fitted on an outer peripheral surface thereof, the sliding sleeve includes an abutting face and a chamber to control the pressing member to press the knob, the base also includes at least one connecting segment disposed on the outer peripheral surface thereof, the sliding sleeve includes at least one coupling segment fixed on the inner surface thereof to engage with the connecting segment.