The invention discloses a purifying treatment device for waste gas. The purifying treatment device comprises a casing, wherein a horizontal water mist casing is arranged at the inner bottom of the casing; a stirring shaft is arranged in the water mist casing; the right end of the stirring shaft is connected with a motor positioned on the outer side of the casing; a plurality of stirring blades arearranged on the stirring shaft; water is held in the water mist casing; a gas inlet pipe is arranged on the upper side of the left end of the water mist casing; a first gas outlet hole is formed in the upper side of the right end of the water mist casing; a blocking plate is arranged above the first gas outlet hole and is in an inverted L shape; a second gas outlet hole is formed in the side wallof the blocking plate; a spraying pipe is arranged above the blocking plate and is connected with a liquid storage tank positioned on the outer side of the casing. The purifying treatment device disclosed by the invention has the beneficial effects that the waste gas is sprayed by using water mist formed by the stirring blades, so that large particle impurities in the waste gas are effectively adsorbed; the arranged spraying pipe is used for further carrying out adsorption treatment on the waste gas. The device has the advantages of good treatment effect on the waste gas and reasonable structural design.