Excellent　soft　magnetic　properties　of　Co-based　metallic　glasses　(MGs)　can　be　achieved　by　appropriate　annealing　treatments.　In　this　study,　the　Co66Fe6Si13B15　MG　was　annealed　by　direct　current　(DC)　with　densities　ranging　from　67　to　333　A/mm(2)　for　varied　periods　of　time.　The　magnetic　properties　of　both　the　as-prepared　and　annealed　samples　were　compared,　which　were　further　correlated　with　microstructure　evolution.　When　the　current　density　is　lower　than　167　A/mm(2),　the　magnetization　increases　from　43　emu/g　for　the　as-prepared　state　to　over　60　emu/g　for　the　annealed　samples,　and　the　coercivity　sharply　declined　due　to　the　stress　release　and　structural　relaxation　caused　by　current　annealing.　Increasing　current　density　leads　to　the　formation　of　nanocrystalline　particles　of　the　size　smaller　than　5　nm,　and　the　magnetic　properties　of　the　composite　material　further　improve,　which　could　be　interpreted　in　terms　of　the　random　anisotropy　model.　The　best　soft　magnetic　performance　with　M-s　of　72　emu/g　and　H-c　of　4　Oe　was　obtained　in　the　sample　after　annealed　with　a　current　density　of　217　A/mm(2)　for　60　s.　Larger　grains　result　in　the　deterioration　of　magnetic　properties　once　the　current　density　exceeds　233　A/mm(2).　The　results　also　imply　that　high-density　but　short-time　current　annealing　can　realize　more　efficient　and　precise　treatment　with　respect　to　industrial　application.