Microstructure,　mechanical　properties,　and　wear　resistance　of　B-bearing　high-speed　steel　(HSS)　roll　material　containing　0.90-1.00%　C,　1.3-1.5%　B,　0.8-1.5%　W,　0.8-1.5%　Mo,　4.6-5.0%　Cr,　1.0-1.2%　V,　and　0.15-0.20%　Ti　were　studied　by　means　of　the　optical　microscopy　(OM),　the　scanning　electron　microscopy　(SEM),　x-ray　diffraction　(XRD),　hardness,　impact　toughness,　and　pin-on-disk　abrasion　tests.　The　results　showed　that　as-cast　structure　of　B-bearing　HSS　consisted　of　alpha-Fe-,　M-23(B,C)(6)-,　M-3(B0.7C0.3)-,　and　M-2(B,C)-type　borocarbides,　a　small　quantity　of　retained　austenite,　and　a　small　amount　of　TiC.　The　hardness　and　impact　toughness　values　of　as-cast　B-bearing　HSS　reached　65-67　HRC　and　80-85　kJ/cm(2),　respectively.　There　were　many　M-23(B,C)(6)-precipitated　phases　in　the　matrix　after　tempering,　and　then,　with　increasing　temperature,　the　amount　of　precipitated　phases　increased　considerably.　Hardness　of　B-bearing　HSS　gradually　decreased　with　the　increasing　tempering　temperature,　and　the　change　of　tempering　temperature　had　no　obvious　effect　on　impact　toughness.　B-bearing　HSS　tempered　at　500　A　degrees　C　has　excellent　wear　resistance,　which　can　be　attributed　to　the　effect　of　boron.