On　the　basis　of　measuring　the　critical　points　and　time-temperature-transformation　(TTT)　curves　of　high　boron　high-speed　steel　(HSS)　roll　alloy,　the　effects　of　quenching　temperature　on　microstructure　and　properties　of　high　boron　HSS　were　researched　by　means　of　optical　microscope　(OM),　scanning　electron　microscopy　(SEM),　X-ray　diffraction　(XRD),　tensile　test,　impact　test　and　hardness　test.　The　results　show　that　high　boron　HSS　has　excellent　hardenability　and　is　easy　to　obtain　martensite　and　its　eutectic　borocarbides　turn　into　the　isolated　distribution　after　quenching.　When　quenching　temperature　exceeds　1050°C,　amount　of　retained　austenite　in　the　quenched　steel　increases　and　the　hardness　decreases.　Tensile　strength　and　impact　toughness　of　high　boron　HSS　increase　as　quenching　temperature　is　increased　from　950　to　1050°C.　Tensile　strength　has　no　significant　change　when　quenching　temperature　exceeds　1050°C　and　impact　toughness　has　slight　decrease　when　quenching　temperature　exceeds　1050°C.　High　boron　HSS　has　excellent　comprehensive　mechanical　properties　quenching　at　1050°C.