Si-doped　hexagonal　boron　nitride　nanosheets　(Si-BNNS)　and　nanotubes　(Si-BNNT)　have　been　investigated　by　first-principle　methods.　The　strong　interaction　between　the　silicon　atom　and　the　hexagonal　boron　nitride　nanosheet　or　nanotube　with　a　boron　vacancy　indicates　that　such　nanocomposites　should　be　very　stable.　The　significant　charge　transfer　from　the　Si-BNNS　substrate　to　the　O-2　molecule,　which　could　occupy　the　antibonding　2　pi*　orbitals　of　O-2,　results　in　the　activation　of　the　adsorbed　O-2.　The　catalytic　activity　of　the　Si-BNNS　for　CO　oxidation　is　explored　and　the　calculated　barrier　(0.29　eV)　of　the　reaction　CO　+　O-2　-＞　CO2　+　O　is　much　lower　than　those　on　the　traditional　noble　metals.　This　opens　a　new　avenue　to　fabricate　low　cost　and　high　activity　boron　nitride-based　metal-free　catalysts.