Formaldehyde cross-linked chitosan was used to adsorb sulfate ions from aqueous solution in this study. Batch experiments were conducted to investigate the conditions of the adsorption, the isotherms and kinetics of the adsorption. The optimized conditions of adsorption were as follows: the adsorbent dosage was 0.5g, the equilibrium time was 240min, the initial concentration of sulfate ions was 153.3mg/L, the temperature was 50°Cand the value of pH was 2.2. The maximum adsorption capacity came up to 14.7 mg/g with the adsorption efficiency got to 95.7%. The equilibrium data fitted Langmuir isothermal model well. In addition, the adsorption process could be explained by the second-order kinetic model, and the chemisorption was the limit step for adsorption velocity.