The invention discloses a tail gas purifying device which comprises a purifier case, a first grid and a second grid. The surface of the purifier case is provided with a rectangular window. The two ends of the purifier case are connected with a first front end cover and a rear end cover respectively. The four surfaces of the purifier case are connected with four fixing devices respectively. A second front end cover is connected with the first front end cover. A third front end cover is connected with the second front end cover. The first grid and the second grid are arranged in the purifier case. The tail gas purifying device has the advantages of being reasonable in design and good in universality, the tail gas purifying device does not fall easily in the use process, and the grids are convenient to clean.