Abstract: Factors of various welding heat sources were analyzed.It is found that Gaussian heat source and double ellipsoidal heat source can not indicate welding molten pool exactly in weld simulation.The combined welding heat source which combined Gaussian face heat source with double ellipsoidal body heat source was used in welding simulation.The welding molten pool calculated with the combined welding heat source consists with practice fusion line.The temperature field and stress field of stainless steel by arc welding were simulated with these three kinds of welding heat sources.The residual stress field simulated using the combined welding heat source is in good agreement with test and more exactly than those using the other two heat sources.