The geometry and electronic properties of Bn （n=2—15） clusters with different growth pattern were calculated and analyzed by using the density functional theory at B3LYP level. The energy gap, first ionization potential and binding energy per atom of boron clusters were also discussed. The results show that linear structures are unstable and are strongly metallic, especially for n=8, which has an energy gap as low as 0.061 eV, indicating the metallic characteristic. Planar and quasi-planar structures are most stable and weak in metallicity. The stability and metallicity of tree-dimensional structures are intermediate between those of the linear and the planar or quasi-planar structures. Furthermore, we also analyzed the electronic properties of ground-state clusters, including the binding energy per atom, second difference in energy, energy gap and the first ionization potential. The results show that B12 and B14 are magic-number clusters.