Abstract: A thermal-mechanical nonlinear finite element method based on ABAQUS was developed to simulate the temperature,residual stress and strain fields in thin-walled structures welded by arc fusion welding processes.The welding temperature field and the welding distortion in a thin-walled mild steel pipe were predicted by using the developed finite element method.Meanwhile,experiments were carried out to measure the actual welding distortion in the thin-walled pipe welded by an arc-welding robot.The coincidence between the simulation and the experimental results confirmed the validity of the numerical simulation method.The numerical simulation method has established a foundation for prediction of welding distortion in thin-walled structure used in practical engineering.