Effects　of　casting　thickness　on　microstructure,　mechanical　properties　and　abrasion　resistance　of　Fe-B　cast　alloy　have　been　systematically　investigated.　The　results　show　that　the　microstructures　of　as-cast　Fe-B　alloy　mainly　consist　of　martensite,　pearlite　and　M2B;　with　increasing　of　casting　thickness,　the　V-m/V-p　(where　V,　shows　volume　fraction　of　pearlite　and　V-m　shows　volume　fraction　of　martensite)　decreases,　while　the　morphology,　composition　and　V-b　(volume　fraction　of　boride)　of　Fe-B　alloy　are　nearly　unchanged.　Moreover,　with　increasing　of　casting　thickness,　the　microhardnesses　of　martensite,　pearlite　and　M2B　have　little　change,　while　the　bulk　hardness　of　as　cast　Fe-B　alloy　decreases　in　a　line　relationship　(y　=　-0.33x+64.67)　owning　to　the　decreasing　of　V-m/V-p.　During　wear　process,　the　predominant　wear　mechanism　of　as-cast　Fe-B　alloy　may　change　from　microcutting　to　micro　ploughing　with　decreasing　V-m/V-p,　resulting　in　the　more　and　more　boride　being　crushed　by　F-perpendicular　to.　As　a　result,　the　wear　weight　loss　of　Fe-B　increases　(i.e.　the　abrasion　resistance　decreases)　with　the　decreasing　of　V-m/V-p,　indicating　that　the　V-m/V-p　has　positive　influence　on　abrasion　resistance　of　Fe-B　cast　alloy.