Ferromagnetic layer and dielectric layer of nanometer thickness were deposited alternatively on quartz glass plates to compose nanometer multiple-layers with microwave absorbing function by electrostatic self-assembly. The thickness of a double-layer composed of a ferromagnetic layer and a dielectric layer is 6 similar to 8 nm measured by UV-VS spectrophotometer. The nanometer multi-layer with total thickness of 100 similar to 200 nm exhibits obvious microwave-absorbing effect in the wave range of 8 similar to 18 GHz and the maximum attenuation reaches -16.85 dB. The wave-absorbing mechanism of nanometer multiple-layers was discussed based on the quantum theory.