The　effects　of　quenching　process　on　microstructure　and　hardness　of　High-Boron　High-Speed　Steel　(HB-HSS)　containing　0.4%　C-6.0%　Cr-4.0%　Mo-1.0%　V-1.0%　Si-0.5Mn-x%　B-y%　Al　(x=1.0,　1.5,　2.0,　y=1.0,　2.0,　3.0)　were　investigated　by　means　of　optical　microscopy　(OM),　scanning　electron　microscopy　(SEM),　X-ray　diffraction　(XRD),　and　Rockwell　hardness　tester.　The　experimental　results　indicate　that　the　quenching　microstructure　of　HB-HSS　consists　of　alpha-Fe,　M-2(B,　C),　M-7(B,　C)(3)　and　a　few　of　M-23(C,　B)(6　degrees)　With　the　increase　of　quenching　temperature,　the　net　structure　of　borocarbides　is　damaged　and　the　borocarbides　are　evenly　distributed　in　the　matrix.　When　the　quenching　temperature　is　1050　degrees　C,　the　Rockwell　hardness　of　HB-HSS　increases　with　the　increase　of　boron　content.　The　Rockwell　hardness　of　HB-HSS　decreases　with　the　increase　of　aluminum　content.　When　the　quenching　temperature　is　1050　degrees　C,　the　aluminum　content　is　1.0%　and　boron　content　is　1.0%-2.0%,　the　combination　of　the　microstructure　and　the　hardness　of　HB-HSS　is　the　best.