Abstract: Welding is a sophisticated metallurgical process, numencal simulation of the welding phenomenon with the help of the computer has got more and more wide application. In this article, the concept and analytical methods of numerical simulation and primary coverage and meaning of numerical simulation in welding are introduced; the present state and perspectives of welding numerical simulation at home and abroad in the analysis of thermal process, metallurgical,stress and strain, service performance of component, hydrogen diffusion, special welding process are reviewed. Suggestions for the development of the numerical simulation in welding in china are put forward.