Abstract: Numerical simulation the temperature field of welding with weaving widely adopted was numerically simulated. Heat source model of dynamic weaving arc was developed based on the classical double ellipsoid heat source model according to the character of velocity and direction variation of welding with weaving. Three dimension numerical model of welding with weaving was developed by MARC.MSC software.To verify the calculated results, the temperature was measured by the thermo-couple and the simulated curve agrees approximately with experiment data.Melten pool evolution, transient temperature and peak temperature were determined. Comparing with the results of the welding without weaving, a little peak appears during heating and cooling.Melten pool was multiple heated and cooled and its peak temperature decreased with increasing of weaving velocity.