Simulation of molten flux flow during submerged arc welding was carried out by a hybrid method using Discrete Element Method and Incompressible Smoothed Particle Hydrodynamics method. As a result, flux melting process was calculated with time evolution. Moreover, it was also simulated that molten flux was re-solidified at a backward of a heat source. In this simulation, the average thickness of this slag at z = 5.0±0.25 mm (the center of the wire in the z direction) was estimated to be 4.8 mm. These results showed that the potential and the usefulness of this hybrid method to simulate the flux melting during SAW.