This application discloses a cannula comprising balloon for the direct puncture technique, which includes the first and the second seal assembly, which includes the lower outer casing and the hollow sleeve connected thereto and extending to the distal end. The first seal assembly, the second seal assembly and the hollow sleeve include an instrument access that is communicated and substantially aligned； the hollow sleeve including an inner cylinder surface, an outer cylinder surface and a sleeve-wall therebetween； the distal end of the hollow sleeve further includes an open sleeve lip including a slanted cylinder surface between the opening lip and the transitional lip, the inner and the slanted cylinder surface limiting the sleeve slanted-wall； the balloon assembly includes a balloon axis, a balloon lip and a balloon body coupled thereto, the balloon lip extending distally to form the balloon slanted-wall that matches the shape and size of the sleeve slanted-wall.
