Batch experiments were carried out in order to investigate the adsorption behavior of As (Ⅲ) and As (Ⅴ) affected by activated aluminum. The results show that the adsorption characteristics of As (Ⅲ) and As (Ⅴ) are consistent: 24-hour is enough to obtain equilibrium; The kinetic data correlates well with the pseudo-first-order model; the film diffusion is the rate-limiting step approved by Boyd kinetic model; Compared with the Freundlich model, Langmuir isotherm model offers a better explanation for the adsorption of arsenic onto activated aluminum, indicating the adsorption is mainly monolayer; The obtained mean adsorption energy values calculated from Dubinin-Radushkevich model are lower than 8 kJomol -1, suggesting the adsorption process is physical; The thermodynamic parameters point out that the adsorption is a spontaneous, endothermic process, and the randomness increase at the solid-liquid interface after adsorption.