Abstract: Magnetic nanoparticles have been applied in many fields,such as magnetic fluids,magnetic recording mate-rials,and biological medicine,due to its special properties.A simply discussion about the conventional physical properties,and a detailed discussion about magnetic properties such as superparamagnetism,technical saturation magnetization intensity,coercivity,and critical temperature of three ferriferous oxides [hematite(α-Fe<SUB>2</SUB>O<SUB>3</SUB>),magnetite(Fe<SUB>3</SUB>O<SUB>4</SUB>),and maghemite(γ-Fe<SUB>2</SUB>O<SUB>3</SUB>) were made.Their specific applications in magnetic fluids,magnetic recording materials,biological medicine,catalysts,and microwave absorbing materials were also introduced in detail.At last,prospect of application and research direction of ferriferous oxides was pointed out.