Three-dimensional thermo-mechanical FEM simulations are conducted for the tube plate welding. Different welding processes are simulated base on MARC. The optimization processes is evaluated by simulation results of welding residual stress distribution. The results shows that large welding seam, two sides alternative welding and TIG arc remelt weld toe can reduce stress center in X&Y direction. ultrasonic impact treatment has significant effects on the residual stress and introduces compressive residual stress in the welded joints.