Abstract: To make flocculent magnetic and to treat sewage using magnetic flocculation. Ferriferous polyacrylamide (PAM) composite flocculent was fabricated by swelling the PAM macromolecule in an iron (Ⅱ)/ iron (Ⅲ) solution, followed by an in-situ co-precipitation process. The structure and magnetic properties of the obtained samples were systemically investigated by various techniques. It is found that the composite flocculent is superparamagnetic, with the highest specific saturation magnetization and the coercive force of 9.21 × 10^-3A·m²/ g. The major iron composition in the composite flocculent is characterized as Fe₃O₄ magnetite, which has a mean diameter of 8- 18 nm and distributes evenly in the flocculent. The magnetic flocculent keeps good flocculation property, besides its steady magnetism.Therefore, with the aids of magnetic separation technique, effective flocculating settling can be obtained by using the magnetic flocculent to treat high density slimewater.