During the three-roll planetary rolling, contact region distribution between the roller and workpiece is not only the basis of calculations of rolling force and power, but also the major basis of roll profile design. By considering the constraint conditions based on the movement characteristics of roller and workpiece in the rolling process, the analytical results of contact region distribution were obtained. Counting on the given parameters of rolling process, the specific distribution of contact region was calculated with numerical analysis. As the hypothesis of line contact between the roller and workpiece was not taken in current research, a distribution of contact region was given. The results show that the distribution is not only affected by the rotation radius of planetary gear system, offset angle and inclined angle, but also concerned with the feeding speed of workpiece and the roll speed.