The invention discloses an air ring device for a slag vertical mill, which is positioned at the periphery of a millstone and comprises adjusting plates, an air ring standard block and a baffle plate,the baffle surrounds the millstone by a circle and is fixedly installed on the outer side of the millstone, the air ring standard block is arranged at the bottom of the baffle, and a gap between the air ring standard block and the baffle forms a first channel. A second channel communicating with the first channel is arranged between the air ring standard block and the millstone; the adjusting plates are in an arc shape and fixedly installed on the outer side of the air ring standard block, and the oppositely-arranged adjusting plates are symmetrically installed around the air ring standard block. By changing the area of the air outlet of the air ring, different air speeds are obtained, the purpose of selecting circulating materials at different positions of the grinding area is achieved, the short circuit phenomenon of air flow between the millstone and the air ring standard block is avoided, and the normal working condition of the air flow in the grinding machine is achieved.