In　this　study,　the　microstructural　evolution　and　mechanical　properties　of　a　newly　near　alpha　titanium　alloy　with　trace　additions　of　B　by　in　situ　casting　route　are　investigated.　The　results　show　that　the　coarse　prior　beta　grain　and　alpha　lath　within　matrix　alloy　are　gradually　refined　with　increasing　of　B　addition.　The　relative　refinement　mechanism　of　prior　beta　grain　and　alpha　lath　width　is　analyzed　and　discussed.　In　addition,　it　is　shown　that　both　of　ultimate　compressive　strength　(UCS)　and　yield　strength　(UYS)　increase　with　B　addition,　which　is　mainly　attributed　to　microstructural　refinement.　However,　the　compressive　ductility　and　fracture　toughness　decrease　with　increasing　of　B　addition,　which　is　due　to　the　cracking　of　TiB,　leading　to　the　acceleration　of　crack　extension.