The principle of tube hydroforming such is; The tube is first filled with a liquid emulsion of a water-soluble material, after which the tool is closed. The tube is then forced to adopt the inner contour of the tool by application of an internal pressure and two axial forces. Tube hydroforming has recently drawn the attention of the automotive industries due to its several advantages over conventional forming methods. For a given blank tube and part design ,the success of tube hydroforming process is highly dependent on the loading paths (axial feeding versus internal pressure).If pressure and axial force apply inappropriate, there is the risk of buckling, wrinkling and bust. Considering this, in third chapter of this study is conducted on the analytical solution of tube Hydroforming process. Each count of pressure, axial force and axial stroke in plastic area, depends on two independent parameters ? 1 (increase of tube radius) and ? (stress ratio). Therefore, in fourth chapter is found the appropriate range ? versus increasing tube radius(? 1 ), then for the symmetrical tube with determined geometric and mechanical specifications, loading path (internal pressure – axial stroke) is obtained. Finally, Considering this loading path, in fifth chapter with numerical solution by software ABAQUS, the thickness variation in the middle of the tube was compared with analytical solution. Key Words tube hydroforming ,loading ,pressure ,stroke
