Behaviors　of　ultrathin　metallic　nanowires　under　strain　conditions　have　attracted　plenty　of　interest　due　to　their　unique　properties　and　structures.　Here,　for　the　first　time,　we　provide　direct　atomic-scale　observations　of　the　reversible　chiral　structure　transformation　of　the　gold　nanowire　under　tensile　strain　conditions　in　transmission　electron　microscopy.　The　formation　and　disappearance　of　a　(111)　projection　in　the　(110)　projected　nanowire　were　observed　during　the　structural　transformation.　We　reveal　that　the　chiral　structure　transformation　is　induced　by　the　nanowire　twisting　behavior,　which　is　achieved　via　atomic　plane　rotation　and　nanowire　bending.　Our　results　provide　direct　evidence　for　an　expressive　and　deterministic　reversible　transformation　from　a　symmetrical　face-centered-cubic　structure　to　the　chiral　structure　of　gold　nanowires,　which　enables　an　atomic-scale　understanding　of　the　behavior　of　ultra-thin　nanostructure　and　provides　guidance　in　the　design　of　nano-devices.