Prediction of welding distortion of stainless steel welding joint in reasonable time is meaningful in welding industry. In this paper, a three dimensional thermo-elastic-plastic finite element method (FEM) is developed to precisely predict welding distortion on bead on plate welding with 304 stainless steel. Meanwhile, the corresponding experiments are carried out to validate the predicted results. Research results show the predicted results by FEM match the experimental results very well. In the condition of different welding heat input, the welding heat input play an important role on welding distortion. While, material properties of stainless steel play a larger role on welding distortion when welding heat input is same. Further, for bead on plate welding of thin plate, both large distortion theory and small distortion theory are computed. The results show that using large distortion theory is more accurate in prediction welding distortion on thin plate welding.