In this paper, the cold upsetting-extruding process of a tube flange is discussed in detail. Finite element method (FEM) simulation, using the program DEFORM2D, was carried out to analyze the in fluence of the tube dimensions and interface friction on the material flow and the cause of forming defects. Based on the FEM simulation results, the relational curves between the flange width and the extreme friction factors were established. The concept of a forming limit diagram for cold upsetting±extruding of a tube flange is presented. The results from the process simulation were then used in tube blank and die plan and lubricant selection. The subsequent experimental results showed reasonable agreement with the numerical simulation results.