The aqueous solution of chromic acid or chromic acid mist has great pollution to the environment. Chromic acid is used as raw material in surface treatment industries such as chromium plating, roughening, passivation and metal processing. The treatment of chromic acid is generally divided into discharge treatment and recovery treatment. The former will consume a lot of chemical raw materials, manpower and other treatment costs to meet the discharge requirements, while the latter can make a lot of waste chromic acid or chromium fog reuse, greatly reducing the treatment cost.