Abstract: According to the multi-pass groove rolling characteristics of metal closed cold roll forming, complex contour of shape tubes was described with the biarc interpolation function. The description considered the existence of topological equivalence relations and the fixed point property of the boundary region between the round tube billet contour before rolling and the shape tube contour after rolling. The centroid mapping mathematical model was established between them. The roll flower of closed cold roll forming process of shape tubes was drawn. The cold rolling experiment of the scallop tube was carried out on the test mill using the aluminum alloy round tube as the blank. The results show that the inner and outer contours of the scallop tube are compliant without bumps after rolling. The wall thickness deviation is less than ±0.5 mm, and the angle error is less than ±1.5°. They meet the requirement of the GB/T 6728-2002 standard. The study provides a new method for the roll flower design of the cold roll forming of shape tubes.