The　continuous　cooling　transformation　(CCT)　curve　of　an　Fe-2.1B　(wt%)　alloy　is　obtained　using　a　Gleeble　1500D　thermomechanical　simulator.　The　microstructure,　mechanical　properties,　and　residual　stress　of　alloy　specimens　with　various　cooling　rates　are　examined.　The　results　reveal　that　the　cooling　rate　has　a　great　influence　on　the　matrix　microstructure　of　the　Fe-2.1B　(wt%)　alloy.　Pearlite　is　formed　at　the　cooling　rate　of　0.1　K/s,　pearlite　and　martensite　are　formed　in　the　cooling　rate　range　of　0.2-0.5　K/s,　and　only　martensite　remains　in　the　matrix　when　the　cooling　rate　exceeds　0.5　K/s.　In　addition,　as　the　cooling　rate　increases,　the　dislocation　density　in　the　matrix　increases,　and　this,　in　turn,　leads　to　an　increase　in　the　volume　fraction　of　the　M-23　(B,C)(6)　phase.　The　precipitation　of　M-23(B,　C)(6)　causes　the　decrease　in　the　(B　+　C)　contents　of　the　matrix,　which,　in　turn,　reduces　the　microhardness　of　the　matrix　to　some　extent.　Meanwhile,　the　large　residual　compressive　stress　of　the　alloy　increases　with　increasing　cooling　rate.　The　maximum　residual　compressive　stresses　induced　by　the　cooling　rates　of　0.5　and　30　K/s　are　approximately　18%　and　36%,　respectively,　higher　than　that　induced　by　the　cooling　rate　of　0.1　K/s.　Moreover,　when　the　cooling　rate　increases　from　0.1　K/s　to　0.5　K/s,　the　macrohardness　and　bending　stress　increase　significantly　owing　to　an　increase　in　V-m/V-pr　(where　V-m　represents　volume　fraction　of　martensite,　V-pr　is　the　volume　fractions　of　pearlite　and　austenite).　When　the　cooling　rate　exceeds　0.5　K/s,　the　macrohardness　and　bending　stress　decrease　gradually　because　of　the　decrease　in　the　(B　+　C)　contents　of　the　matrix　and　an　increase　in　the　residual　stress.　The　critical　cooling　rate　(0.5　K/s)　may　be　the　optimal　cooling　rate　of　Fe-B　alloys.