本發明有關一種以淨水污泥製備鐵錳氧化磁體之方法。在此製備鐵錳氧化磁體之方法中，首先係準備淨水污泥，該淨水污泥中包括鐵、錳金屬；接著，利用一酸洗液浸漬該淨水污泥而溶出淨水污泥中的鐵、錳金屬離子；然後，將酸洗液所浸漬的含鐵錳溶液與污泥分離且以還原劑還原；接著，將含鐵錳溶液進行高溫燒結反應以形成具有鐵錳氧化磁體的成品。 The present invention relates to a method for preparing magnetic ferromanganese oxide (MnFe2O4) from drinking-water treatment sludge. In the method for preparing magnetic MnFe2O4, at first, a drinking-water treatment sludge including iron and manganese metal is prepared. Thereafter, the iron and manganese metal ions in the drinking-water treatment sludge are dissolved by immersing the drinking-water treatment sludge with an acid pickling solution. Then, the ferromanganese solution immersed in the acid pickling solution is separated from the sludge and reduced with a reducing agent. Thereafter, the ferromanganese solution is subjected to a high-temperature sintering reaction to form a product including magnetic ferromanganese oxide.