Studies　have　shown　that　the　crystallization　phase　state　of　Ge2Sb2Te5　(GST)　can　be　reversibly　modulated　by　femtosecond　(fs)　laser　multiple　pulses,　which　have　excellent　applications　in　reconfigurable　multi-level　operation　fields.　In　this　study,　the　temporal-spatial　crystalline　evolution　dynamics　of　amorphous　GST　film　is　investigated　during　two　fs　laser　pulses　excitation　through　a　pump-probe　shadowgraph　imaging　technique.　A　quasi-amorphous　phase　state,　which　is　different　from　that　in　the　initial　as-deposited　amorphous　GST,　is　emerged　through　the　first　fs　laser　pulse　excitation　with　a　pulse　energy　lower　than　crystallization　threshold.　The　experimental　results　reveal　that　a　crystallization　enhancement　effect　can　be　induced　through　the　second　pulse　excitation　based　on　this　quasi-amorphous　surface　structure.　The　stimulative　cluster　generated　in　the　quasi-amorphous　reduces　the　amorphous-to-crystalline　phase　transition　threshold　for　the　second　fs　laser　pulse　irradiation.　The　spatially-resolved　phase-transition　threshold　extension　effect　in　a　horizontal　direction　is　proposed　with　the　increasing　pulse　number　to　summarize　the　mechanism　of　the　crystallization　enhancement　effect.　The　specific-grain-appearance　(coarse　grains　and　fine　grains　representing　different　phase　transition　approach)　distributed　area　induced　by　single　and　double　fs　laser　pulses　irradiation　are　experimentally　demonstrated　corresponding　to　threshold　extension　theory.