Directional　curvature　K-D,　was　proposed　as　a　simple　and　efficient　criterion　for　the　formation　energies　and　reactivities　of　defects　in　carbon　and　boron　nitride　nanotubes.　Using　the　periodic　density　functional　theory,　the　formation　energies　of　Stone-Wales　(SW)　and　divacancy　(DV)　defects　in　their　armchair　(5,5)　and　zigzag　(10,0)　nanotubes,　as　well　as　the　binding　energies　of　the　O　atom　adducts　on　these　defect　sites　are　calculated.　These　calculated　results　are　found　to　fit　well　with　the　theoretical　predictions　by　the　directional　curvature　K-D.