The stainless steel tee is a pipe fitting for a pipe branch. For the use of seamless pipe manufacturing tees, the current commonly used technology is hydraulic bulging and hot forming two kinds. The hydraulic bulging of stainless steel tee is a forming process of compensating the bulging of branch pipe through the axial direction of metal material. The process is to use special hydraulic press, with three links within the tube billet diameter equal injection liquid, through the two horizontal side of the hydraulic cylinder synchronization of the motion of tube billet, billet after squeezed smaller volume, smaller volume of liquid with the tube billet inside the tube billet and the pressure increases, when the stainless steel tee branch pipe bulge out to the pressure, the metal material in the liquid in the cylinder and the pipe pressure under the dual role of flow along the mold cavity and the branch pipe.