Defect　directional　curvature　KD-def　was　proposed　as　a　reasonable　criterion　for　the　reactivities　and　adduct　structures　at　the　defective　region　of　single-walled　carbon　nanotubes　(SWCNTs).　B3LYP/6-31G*　calcWations　for　the　[2　+　1]　and　[1　+　1]　additions　of　a　series　of　11-layer　(n,　n)　(n　=　4-8)　and　six-layer　(10,0)　SWCNTs　with　Stone-Wales　defects　showed　that　the　KD-def　or　it,　mean　KM-def　was　a　good　index　to　judge　the　adduct　structures　and　the　reactivities.　Adducts　of　the　[2　+　1]　additions　were　divided　into　two　types:　one　was　the　adduct　with　the　C-X-C　configuration　and　corresponding　to　the　large　KD-def　and　the　large　binding　energy,　and　another　was　the　adduct　with　the　closed　-3MR　structure　and　corresponding　to　the　small　KD-def　and　the　small　binding　energy.　It　must　be　pointed　out　that,　besides　mainly　relying　on　the　KD-def,　the　adduct　structures　and　the　reactivities　of　the　[2　+　1]　additions　had　been　weakly　affected　by　topologic　structures.　The　calculated　results　for　the　[1　+　11　additions　of　the　11-layer　(5,5)　SWCNT　with　defect　A　revealed　that　the　binding　energies　monotonously　increased　with　the　KM-def.　(C)　2008　Wiley　Periodicals,　Inc.　Int　J　Quantum　Chem　109:　668-678,　2009