Three-dimensional　finite　element　method　simulation　and　experimental　investigation　were　employed　to　study　the　fast　crystallization　mechanism　of　Ge2Sb2Te5　phase-change　alloy　films　induced　by　a　short　Gaussian　laser　pulse.　A　crystallization　mechanism　was　proposed　which　took　into　account　the　roles　of　heating　and　cooling　rates　on　crystallization　of　the　phase-change　materials.　Microstructure　characteristics　of　crystallization,　primarily　attributed　to　inherent　material　properties　and　temperature　field,　were　discussed.　The　present　study　not　only　unveils　the　crystallization　mechanism　induced　by　laser　radiance　but　also　distinguishes　the　roles　of　the　ultrahigh　heating/cooling　rate　for　the　phase　transition.　(C)　2013　AIP　Publishing　LLC.