A flexible vertical grinder, having a main shaft mounting frame (4) on a grinder frame (1); a main shaft (3) is mounted on the main shaft mounting frame; a stelliform bracket (9) is mounted on the main shaft; a hammer wheel grinder and a material-sorting balance wheel device are mounted on the stelliform bracket; the material-sorting balance wheel (4) and the hammer wheel (17) are on the same horizontal plane. The vertical grinder can apply different grinding forces according to different specific surface areas of the to-be-ground material, and can grind materials of different grades properly but not excessively, thus greatly improving crushing efficiency, having good overall rigidity and stable operation, and facilitating maintenance.