Abstarct: The elastomeric tool is widely used in the aviation and automobile industry due to its high flexibility, good surface quality and cost reduction. In this thesis a new method for producing a T-branch joint by using an elastic medium to apply double-sided pressure both inside and outside of the tube is presented. Numerical analysis of the process by assuming an incompressible hyperelastic material with Mooney-Rivlin behavior model for elastic tool in Abaqus software was performed. For tube the elastic-plastic model with normal anisotropy and FLD damage criterion was used. Taguchi test method was used to determine the effective intrinsic and extrinsic parameters on branch height and thickness reduction percentage. The statistical analysis of this design showed that the rubber hardness, the distance between punch shouldered and tube edge, the die corner radius and the tube thickness have the greatest effect successfull of the process. In the next step, in order to achieve the optimal values of effective factors, the response surface method was used with nonlinear regression model. In the experimental section, standard tests to extract the mechanical properties of three copper, brass and aluminum tubes, and two types of elastomeric polyurethane and PVC tools were performed. The manufacturing of the die after assuring the optimal design with the help of the 3D finite element method‌ was carried out. Three intact sample of copper, brass and aluminum tubes after initial tests was successfully produced. For validation of experimental and numerical results, strain distribution and tube thickness in longitudinal and circumferential paths were compared. The results showed that, firstly, the idea of using both inner and outer pressure on tube walls is on oppropriate technique to fabricate a defect-free long T-branch. Furthermore the simulation results have an acceptable accuracy.