The present invention relates to hot-rolled pipe elongation technique. Said technique can be directly used in skew-rolled pipe elongation equipment. Said invention provides a new geometrical model of pipe material elongator. It is basically characterized by that its rolls are arranged according to convergent form, namely, the cone angle Psi is less than O, in the coordinate system oxyz, the offset amount yo is not equal to O, and its feed angle beta and the offset amount yo can not be identical in size. Besides, said invention also provides four sets of equations, and utilizes them to make optimization calculation so as to obtain the invented geometrical model of skew-rolled pipe material elongator.