The utility model discloses a rolling pipe expander belonging to a rolling device of a metallic pipe, which is composed of an inner deformed tool, a positioning movable device 100 of the inner deformed tool, a material conveying device 200, an outer deformed tool, and the positioning guiding device 300 of the outer deformed tool, a main gearing 400, and a discharge device 500. The utility model is characterized in that a top head handling device 600 is additionally arranged; the inner deformed tool 101 is a core rod or a top head. The outer deformed tool and the positioning guiding device 300 thereof correspond to the core rod or the top head. A movable positioning device 700 is arranged to cause the main gearing 400 to move and position. The utility model is characteristics of double uses for pipe rolling and pipe expanding, simple structure, and low cost, and the specification and range of the section metal pipe can be increased.