Reversible　phase-change　behaviors　of　Ge-Sb-Te　based　superlattices　(GST-SL)　were　studied　by　ab　initio　molecular　dynamics　(AIMD)　simulations　based　on　three　models　containing　Ge/Sb　intermixing,　namely　the　Petrov-mix,　Ferro-mix,　and　Kooi-mix　models.　The　flipping　behavior　of　Sb　atoms　was　found　in　all　the　three　GST-SL　models　in　the　melting　process.　Among　them　the　Kooi-mix　model　exhibited　the　best　stability,　and　the　analyses　of　bond　length　distribution　and　electron　localization　function　provided　a　better　explanation　on　the　phase　transition　of　GST-SL.　Finally,　we　proposed　a　fast　switching　model　for　GST-SL　based　on　Sb　flipping.