The　elaborated　model　solves　the　coupled　equations　of　a　laminar　fluid　flow　and　heat　transfer　to　predict　the　temperature　distribution　in　the　weld　pool.　The　enthalpy-porosity　technique　was　employed　to　account　for　the　latent　heat　during　melting　and　solidification.　The　coupled　effects　of　buoyancy　and　Marangoni　forces　are　considered　in　this　model.　The　volume-of-fluid　(VOF)　method　was　employed　to　track　free　surfaces　of　weld　pool.　The　molten　temperature　distribution,　velocity　field　and　molten　shape　were　calculated　using　FLUENT　software.　The　results　clearly　demonstrate　Marangoni　flow　significantly　alters　the　characteristics　of　the　thawing　and　solidifying　process,　and　makes　the　molten　wider　and　shallower.