Geometrical and electronic properties of As-n (n = 2-15) neutrals, cations and anions have been investigated using the density functional method of B3LYP. Berny structural optimization and frequency analyses are performed with the basis of 6-311 + G(d) for both neutrals and charged ions. The total energies of these clusters are then used to study the evolution of their binding energy, relative stability, and electronic properties as a function of size. The geometries are found to undergo a structural change from two dimensional to three-dimensional when the cluster contains four atoms. The geometrical changes are companied by corresponding changes in the nearest-neighbor distances and coordination numbers. In the whole size range, both ionization potential and electron affinity have the tendency of decrease when the number of As units in the cluster increases. The stability of clusters exhibits strong even-odd alternations with several magic numbers. The neutral As (n) clusters are found to be even-numbered with local maxima at n = 2 and 4, while the cationic and anionic clusters are preferentially odd-numbered with As-3(+), As-5(+) and As-5(-) being the most stable ions according to the calculated results of the both energy gain and electronic properties.