Abstract: The graphene oxide (GO) was preparaed by natural flake graphite, then it was reduced to graphene(RGO) by Zn. ZnO is attached to the surface of RGO. The structure, morphology, degree of oxidation, electromagnetic loss properties, Debye relaxation and microwave absorbing properties of ZnO/RGO composite were investigated by XRD, Raman, SEM, TEM, FTIR and vector network analyzer (VNA). The results show that when the reduction temperature is 50℃, the structure of RGO is more complete after reduction and the layer spacing is 0.89 nm, the permittivity and permeability of ZnO/RGO composite are higher. At 17.15 GHz, the reflectivity of ZnO/RGO composite is -41.2 dB, the bandwidth of the reflection loss of ZnO/RGO composite below -10 dB is 3.67 GHz.