Plasma　sprayed　coatings　are　built　up　by　the　accumulation　of　splats　formed　by　the　impacting,　spreading　and　solidifying　of　molten　droplets　on　the　substrate.　A　three-dimensional　computational　model　including　heat　transfer　and　solidification　is　established　to　simulate　the　formation　process　of　a　single　splat　using　the　computational　fluid　dynamics　(CFD)　software,　FLUENT.　The　fluid　flow　and　energy　equations　are　discretized　and　solved　according　to　typical　finite　volume　method　on　an　unstructured　grid.　A　volume　of　fluid　(VOF)　tracking　algorithm　is　used　to　track　the　droplet　flow　with　free　surface.　In　order　to　understand　the　splat　formation　mechanism,　the　process　of　splat　formation　caused　by　impacting　and　spreading　of　a　molten　nickel　droplet　on　a　polished　mild　steel　surface　is　simulated.　On　this　basis,　the　simulations　of　impact　of　a　molten　droplet　on　substrate　with　different　conditions　including　the　surface　morphology,　thermal　conductivity,　initial　temperature　of　the　substrate　and　the　thermal　contact　resistance　are　presented.　The　results　clearly　show　the　effect　of　those　parameters　on　the　shape　of　the　final　splat　and　splash　behaviors.　©　Shanghai　Jiaotong　University　and　Springer-Verlag　Berlin　Heidelberg　2011.