One big issue in electromagnetic interference (EMI) shielding is ignored, that is no consideration of friendliness to overall environment. Developing green EMI shielding materials is significantly imperative, because strong secondary reflection causes extra environment burden and worsening hazard. However, synergy of high efficiency and less secondary reflection remains challenging. Herein, learning from brilliant wisdom of nature, 3D eco-mimetic nanoarchitecture is constructed for the first time, successfully approaching green efficient EMI shielding. It features 3D hierarchical dual conducive nets, microcosmically reconstructing both spatial and functional characteristics of natural electromagnetic attenuation system, with highly integrated functions. Its shielding effectiveness (SE) and green shielding index (g(s)) can be increased by tailoring graphene cycles, showing potential for dual functions of electromagnetic wave absorbing and shielding. The SE reaches similar to 54 dB with favorable g(s) ( similar to 1.44), low density (similar to 0.1 g/cm(3)), and good thermal stability ( similar to 96%). This arises from synergy of promoted electron hopping, induced multiple polarization centers, assembled magnetic resonance and especially, equivalent wedge effect of honeycomb-like surface. Our findings dig out a new way for developing electromagnetic multifunctional materials with light weight, high efficiency and eco-friendliness in the future.