Improved puncture expansion sheath

The utility model discloses an improved puncture dilation sheath, which relates to the technical field of medical instruments and comprises a dilation tube, a sheath tube is sleeved on the outer wall of the dilation tube, a sheath tube joint is fixedly mounted on the outer wall of the top of the sheath tube, a liquid storage cavity is fixedly mounted on the outer wall of the right side of the sheath tube joint, and a liquid outlet tube is arranged on the outer wall of the sheath tube joint. After liquid in the sheathing canal is injected into the liquid storage bottle through the liquid outlet pipe under the condition of negative pressure, the liquid storage bottle can be pulled out by rotating the liquid storage bottle mounting plate during cleaning, and the liquid storage bottle cap is sealed through the one-way soft plate when the liquid outlet pipe is separated from the liquid storage bottle cap, so that liquid leakage is prevented; the liquid storage bottle can be independently cleaned by rotating the li