Wave-absorbing coating samples were fabricated with nano tetraleg ZnO as the absorbent and epoxy resin as the binder. The influence of the content of nano tetrapleg ZnO in the absorbing coatings and the thickness of the coatings on wave-absorbing property was investigated. The results showed that excellent absorption was observed in the wave band from 15GHz to 18GHz when the coating thickness was 15mm. When the coating thickness increased to 35mm, the wave-absorbing property of the samples was improved significantly, especially in the wave band from 6GHz to 11GHz. The frequency width reached 136GHz (44—18GHz) when the reflection value of the samples was below -5dB, its wave-absorbing property has obviously improved compared with that of the micrometer sized ZnO. Finally, the wave-absorbing mechanism of nano tetraleg ZnO was discussed. Such coatings are of great values in applications involving electromagnetic wave shielding.