A novel dry phantom nanoconducting composite that can simulate the effect of electromagnetic wave on human tissues composed of graphite/nickel (GN) nanoparticles and polyvinyl chloride (PVC) was successfully fabricated. The morphology of as-synthesized graphite nanosheets and PVC/GN composites was investigated by means of scanning electron microscope. Dielectric parameters such as relative permittivity, imaginary permittivity, and alternating current conductivity are evaluated in the frequency range of 0.5–12 GHz. The results are compared with the in vitro equivalent human tissue data and good agreement is reported. The absorption and reflection coefficient as a function of frequency of nanocomposites were also studied. The novel PVC/GN nanocomposites have potential applications for dry phantom and the coupling media in microwave medical imaging.