The invention discloses a method and system for preparing metallized pellet through red mud. The method comprises following steps: red mud, calcium oxide and hot water at the temperature of 80 DEG C to 100 DEG C are mixed evenly, and red mud is washed; the washed red mud is subject to sedimentation and filtering, and red mud containing water and filtrate are obtained; the red mud containing water is dried, and dried red mud is obtained; the dried red mud and reduction coal are mixed and formed, and the pellet is obtained; the pellet is dried and then is subject to direct reduction, and the metallized pellet is obtained. The calcium oxide is added in the red mud washing process, sedimentation of the red mud is promoted, and the subsequent direct reduction process of the red mud is facilitated.