The comparison of conventional and ultrasound-assisted removing of chlorine from aluminum dross was carried out, and the mechanism of ultrasonic enhancement was studied by taking the aluminum dross from an aluminum manufacturer as the research object. The results showed that the best conditions for chlorine removing were as follows: pH of 4, liquid?solid mass ratio of 2, ultrasound power of 150 W and sonication time of 1 h. Under ultrasonic activation, product layer can be peeled, new surfaces was expose, reaction resistance was reduced, the liquid?solid reaction was promoted, leaching rate was improved and leaching time was greatly shortened. The aluminum dross after chlorine removed can be used as raw materials back to the electrolysis. Ammonia and NaCl products could be obtained by collecting ammonia with water and evapo`ration and concentration of leaching liquid, respectively. Aluminum dross was comprehensivly utilized.