With the progress of computer technology and the development of finite element algorithm, the modeling and numerical simulation in welding engineering has been widely used, and many problems such as welding temperature field, stress field, deformation, microstructure, life prediction and structural integrity have been solved. However, the uncertainty of modeling and simulation has been throughout the whole technology It mainly includes the uncertainty of parameters, the accuracy of model, the uncertainty of data, the incompatibility of grid, the independence of step size and the contradiction between convergence and accuracy. It is necessary to carry out research on the verification and validation of modeling and simulation, and further promote the reliability of modeling and simulation by combining with new technologies such as standardization, artificial intelligence and digital twins.