Co/C/Fe/C core-shell hierarchical flowers (CSHFs) with various compositions and surface morphologies were fabricated by hydrothermal-chemical vapor decomposition. Surface-dependent electromagnetic properties were investigated at 2-18 GHz. Due to the localized surface plasmon resonance and coupling, Co/C/Fe/C CSHFs with strawberry-like surface exhibit significantly enhanced permittivity, permeability, exchange resonances, and attenuation compared with Co-HFs and Co/C/Fe/C CSHFs with compact particle film. Such performances enable Co/C/Fe/C CSHFs to become excellent absorbers with strong absorption, broad bandwidth, and light weight. This finding demonstrates that the surface and interface designs of plasmonic heterostructures are critical to improve microwave absorption properties for future application.