In　a　reference　frame　attached　to　the　moving　heat　source,　for　example,　surface　remelting,　a　fixed　grid　enthalpy-porosity　method　was　used　to　deal　with　phase　change　problem,　and　the　momentum　and　energy　changes　caused　by　moving　heat　source　were　taken　as　additional　sources　to　formulate　control　equations　which　are　discretized　and　solved　using　control-volume-based　computational　method.　Heat　transfer　,　phase　change　and　fluid　flow　in　melted　pool　could　be　simulated.　With　the　developed　software,　the　temperature　and　velocity　fields　of　stainless　steel　for　different　laser　iuput　powers　and　same　scanning　velocity　during　laser　remelting　have　been　calculated　and　analysized.