Sodium　(Na)　metal　anodes　receive　significant　attention　due　to　their　high　theoretical　specific　energy　and　costeffectiveness.　However,　the　high　reactivity　of　Na　foil　anodes　and　the　irregular　surfaces　have　posed　challenges　to　the　operability　and　reliability　of　Na　metals　in　battery　applications.　In　the　absence　of　inert　environmental　protection　conditions,　constructing　a　uniform,　dense,　and　sodiophilic　Na　metal　anode　surface　is　crucial　for　homogenizing　Na　deposition,　but　remains　less-explored.　Herein,　we　fabricated　a　Tin　(Sn)　nanoparticle-assembled　film　conforming　to　separator　pores,　which　provided　ample　space　for　accommodating　volumetric　expansion　during　the　Na　alloying　process.　Subsequently,　a　seamless　Na-Sn　alloy　overlayer　was　formed　and　transferred　onto　the　Na　foil　during　Na　plating　through　a　separator-assisted　technique,　thereby　overcoming　conventional　operational　limitations　of　metallic　Na.　As　compared　to　traditional　volumetrically　expanded　cracked　ones,　the　present　autotransferable,　highly　sodiophilic,　ion-conductive,　and　seamless　Na-Sn　alloy　overlayer　serves　as　uniform　nucleation　sites,　thereby　reducing　nucleation　and　diffusion　barriers　and　facilitating　the　compact　deposition　of　metallic　Na.　Consequently,　the　autotransferable　alloy　layer　enables　a　high　average　Coulombic　efficiency　of　99.9　%　at　3.0　mA　cm　-2　and　3.0　mAh　cm　-2　in　the　half　cells　as　well　as　minimal　polarization　overpotentials　in　symmetric　cells,　both　during　prolonged　cycling　1200　h.　Furthermore,　the　assembled　Na||Sn-1.0h-PP||Na　3　V　2　(-　PO　4　)　3　@C@CNTs　full　cell　delivers　high　capacity　retention　of　97.5　%　after　200　cycles　at　a　high　cathodic　mass　loading.