Abstarct: Tube hydroforming is a relatively new process of tube forming which is taken into consideration by automotive and aerospace industry due to its greater stiffness to weight ratio, lower tooling cost and manufacturing steps. In this process tube is placed in a die and it will fill the die cavity by applying internal fluid pressure and axial feeding. Several researches performed in order to improve formability and efficiency of this process. In this thesis, increasing of tube formability by using a new method of hydroforming process has been investigated. At first a hydroforming die is designed to form an “I” section tube. In order to obtain the mechanical properties of as received and annealed tube a series of uniaxial tensile test is preformed. Finite element analysis of the hydroforming process was carried out using conventional methods and proposed method in this study. Comparing the results of these two analysis, it was found that by using the proposed method of this thesis, at the same fluid pressure, the tube formability of the as received and annealed tubes increased by 17% and 30% respectively. In addition to that it was found that the fluid pressure required to obtain a certain section height is reduced by 53% and 90% for as received and annealed tube respectively. After ensuring the results of analyzes, the hydroforming die was constructed. To maintain the die symmetry during closure, a four-lixnkage mechanism was used. Tests were carried out according to finite element analysis for as received and annealed tubes for conventional and proposed methods. The section height and volume of the tube were compared with the results of finite element analysis, which consistently correlated with the results.