The invention discloses a mechanical sealing device for a kettle. The mechanical sealing device comprises an outer shell and a rotating shaft penetrating the outer shell, a movable ring is arranged on the rotating shaft, a fixed ring base is arranged on the outer shell, and a fixed ring is installed on the fixed ring base; one end of the movable ring abuts against the fixed ring, a transmission base is arranged on the rotating shaft, and an embedding part, a first boss and a second boss are sequentially arranged on the transmission base from inside to outside; and a first concave table, a second concave table and a fixing part are sequentially arranged on the movable ring from inside to outside. According to the mechanical sealing device for the kettle, the fixing effect of the movable ring is better, the effect of sealing between the movable ring and the rotating shaft is better, the abrasive resistance is good, the service life is long, and convenience is brought to maintenance.