Using quantum mechanics GASTEP software package based on the first principle density function theory (DFT), the electronic structure and optical properties of Ga0.5Al0.5As(1 0 0) beta(2)(2 x 4) reconstruction surface are calculated. Result shows that Ga0.5Al0.5As(1 0 0) beta(2)(2 x 4) reconstruction surface is stable. The calculated work function of Ga0.5Al0.5As(1 0 0) beta(2)(2 x 4) reconstruction surface is 4.811 eV. The band gap of the surface is smaller than the bulk. During the formation of the surface, the electrons move into the bulk and a band-binding region is formed. The absorption peaks move to the high-energy edge and the reflectivity decreases, the static dielectric constant decreases, metal reflective properties region of the surface moves to the low-energy edge and is smaller than the bulk. (C) 2012 Elsevier B.V. All rights reserved.