This study deals with the dimensional accuracy of outer diameter and geometrical workability in rotary swaged product for various process parameters such as percent reduction in outer diameter and the ratio of thickness to outer diameter of a tube. It is generally known that greater cold strengthening is achieved by rotary swaging process rather than by conventional process such as rolling with respect to the same reduction of cross-sectional area. Percent reduction in the diameter and the ratio are considered and selected as important process parameters because of playing a key role during rotary swaging process. In case of tube under rotary swaging process the ratios have influence on geometrically proper workability without defect for different percent reductions in the diameter. In addition the change of metal flow of workpiece under the swaging process is microscopically and globally observed to analyze the reason why dimensional accuracy of the outer diameter of final product is improved after the rotary swaging process. This work might provide available information for the optimum rotary swaging process.