The　Mo-10Si-(0,　5,　10,　15)B　(at.%)　alloys　located　in　Moss　(Mo　solid　solution)　+Mo3Si　+T2　(Mo5SiB2)　region　were　prepared　by　arc　melting.　The　effect　of　B　content　on　the　microstructure,　microhardness,　fracture　toughness　and　oxidation　resistance　of　the　alloys　was　studied.　In　the　Mo-10Si　alloy,　there　are　primary　Mo-ss　and　peritectic　Mo3Si　phases.　With　the　addition　of　B,　(Mo-ss　+　T2)　binary　and　(Mo-ss　+　T2　+　Mo3Si)　ternary　eutectics　emerge　in　Mo-10Si-(5,　10)B　alloys.　For　Mo-10Si-15B　alloy,　primary　Moss　disappears　and　the　mi-crostructure　is　only　composed　of　binary　and　ternary　eutectics.　With　the　increase　of　B　content,　the　proportion　and　grain　size　of　Mo-ss　decrease.　The　microhardness　of　alloys　increases　with　the　increase　of　B　content　due　to　the　increasing　intermetallics.　The　fracture　toughness　of　alloys　decreases　obviously　in　single-edge　notched　three-point　bending　testing　(SENB)　and　the　fracture　mode　transforms　from　transgranular　fracture　to　intergranular　fracture　because　of　the　refinement　of　Mo-ss.　In　the　high-temperature　oxidation　test　at　1250　degrees　C,　the　oxidation　weight　loss　of　the　alloys　decreases　with　the　addition　of　B　due　to　the　densification　of　the　borosilicate　layer.　(C)　2021　Elsevier　B.V.　All　rights　reserved.