Abstract: Colloidal Barium ferrite and colloidal PSS were prepared and nano multilayers were formed on the surface of silicon chip by electrostatic self-assembly.Optimal assembled time and thickness of bilayer were measured by UV-VS spectrophotometer.Surface of multilayers and chemical state of Fe were characterized by SEM and XPS.The wave-absorbing property of multilayers was measured and results show that the radar wave is absorbed between 8GHz and 18 GHz and the maximal reflectivity reaches 16.85dB.The wave-absorbing mechanism was discussed based on quantum theory.