Abstract: The structural evolution and electronic properties of Au_n^- clusters have been studied using density functional theory at the PW91/TZVPP level. The results indicate that all the ground state clusters possess a planar configuration and its growth patterns display an odd-even effect, namely, combined with an Au atom on the high symmetry direction, the Au_n^- cluster with odd n can form the Au_n+1^- cluster by a small relaxation. Simultaneously, the calculated ionization potential based on the ground state is good agreement with experimental value. The energy second-order difference and energy gap show same odd-even oscillation. This implies that the Au_n^- clusters with odd n have higher physical and chemical stability than that with even n.