A manufacturing method of a water-cooling extrusion die sleeve comprises the following steps: Step 1, a die sleeve body cast in one piece is provided with a water inlet and a water outlet; starting with the water inlet, the die sleeve body is horizontally drilled to form a circular hole which is entirely positioned inside the die sleeve body; starting with the above circular hole, the die sleeve body is drilled to form another circular hole, and in this way, circular holes are successively formed and it is guaranteed that all of the formed circular holes are entirely positioned inside the die sleeve body; one end of the finally-formed circular hole overlaps with the water outlet; and Step 2, one or two ends of horizontally and vertically crossed circular holes are blocked to form a closed waterway starting with the water inlet and ending with the outlet. According to the invention, the temperature of the extrusion die sleeve is effectively close to the temperature of cooling water so as to indirectly take away a lot of heat generated by contact between the inner bore of the extrusion die sleeve and external diameter of an extrusion die and reduce the temperature of the extrusion die. Thus, service life of the extrusion die is prolonged, and the overall strength of the die sleeve is not influenced by the method.