Abstract: A waste gas treating device includes two cleansing towers, a plurality of ceramic (or porcelain) balls fully filled in the two towers, and a specific liquid filled in the two towers for waste gas pumped in firstly in the first tower to flow upward through gaps among the ceramic balls and contact with the liquid. Then toxic substances in waste gas react with the liquid to produce byproducts, which sink down out of the first tower and then into a sediment pool. Partial waste gas flowing up to a top end of the first tower is pumped into the second tower for cleansing once again in the same process in the first one to let waste gas cleansed completely and flow out of an upper end of the second tower into atmosphere.