Acid mist waste gas is introduced into the purification tower by the air duct, through the packing layer, the waste gas and sodium hydroxide absorbing liquid for gas-liquid two-phase full contact absorption and neutralization reaction, the acid mist waste gas is purified, and then through the mist elimination plate dehydration and mist removal by the fan discharged into the atmosphere. The absorbing liquid is pressurized at the bottom of the tower by a pump and then sprayed at the top of the tower and then returned to the bottom of the tower for recycling. The purified acid mist exhaust gas meets the emission requirements of local provincial emission standards and is below the emission standards.