Large-diameter thin-wall cylindrical part positioning clamp

The invention discloses a large-diameter thin-wall cylindrical part positioning clamp. The positioning clamp comprises a soft jaw chuck, a supporting sleeve, hoops and bolts, wherein the radian of a positioning molded surface on the inner side of each clamping jaw of the soft jaw chuck is matched with the radian of the outer wall of a thin-wall cylindrical part to be machined; the supporting sleeve is a flexible sleeve with the inner diameter matched with the outer diameter of the thin-wall cylindrical part to be machined; each hoop is an open annular piece formed by machining an elastic metal material, and corresponding bolt connecting holes are formed in the two open ends of each hoop respectively; the end of the thin-wall cylindrical part to be machined is clamped and fixed through the soft jaw chuck; the supporting sleeve is connected to the side wall of the middle of the thin-wall cylindrical part to be machined in a sleeved mode; the hoops are connected to the side walls of the two ends of the supportin