Annular structures of (BN)(x) (2 <= x <= 19) clusters are optimized at DFT/B3LYP/6-3lG* theoretical level. NICS, NBO and MOs are calculated to investigate stability and property. The analyzed results show that (BN), clusters have different bonding characters with the corresponding C-2x molecules. And annular (BN)(x) clusters also have delocalized bonding although they are nonaromatic estimated with NICS values. (BN)(2) has aromaticity for it has different conformation which makes it have special bonding character. (c) 2006 Elsevier B.V. All rights reserved.