In　this　study,　the　influence　of　Fe　doping　on　the　microstructure　and　mechanical　properties　of　Gd-Al-Co　＂metallic　glass＂　fibers　(MGF)　was　systematically　investigated,　and　a　fracture　mechanics　model　was　constructed　based　on　the　fracture　morphology　of　MGF.　Furthermore,　the　mechanism　by　which　Fe　doping　improves　the　mechanical　properties　was　revealed.　The　results　indicate　that　the　Gd-Al-Co-Fe　series　MGF　has　a　typical　amorphous　structure,　and　with　an　appropriate　amount　of　Fe　increases　the　order　degree　of　structure　j,　indicating　that　a　small　number　of　nanocluster　micro-regions　are　formed　on　the　amorphous　matrix.　With　an　increase　in　Fe　doping,　the　tensile　strength　of　MGF　presents　an　initial　increase　and　subsequent　decrease.　The　tensile　strength,　Rm,　of　the　GdAlCoFe2　MGF　was　the　largest　(up　to　1199　MPa),　and　its　fracture　reliability　was　also　superior　(the　threshold　value　of　fracture　was　581.93　MPa).　The　tensile　fracture　of　the　Gd-Al-Co-Fe　series　MGF　is　a　flat　fracture,　showing　the　characteristics　of　brittle　fracture,　with　vein-shaped　patterns,　splitting,　and　shear　bands.　A　specific　amount　of　nanocluster　micro-regions　formed　by　Fe　doping　effectively　hindered　the　growth　rate　of　crack　tips　during　the　stretching　and　deformation　of　the　microfibers,　and　significantly　improved　the　mechanical　properties　of　the　Gd-Al-Co-Fe　series　MGF.　This　study　lays　the　foundation　for　its　engineering　applications　in　the　fields　of　mechanics　and　machinery.　(C)　2021　The　Authors.　Published　by　Elsevier　B.V.