The fabrication of graphitized diamond covered with polypyrrole (D@G@PPy) core-shell nanocomposites has been achieved by using a superficial electrochemical polymerization and self-assembly strategy. The conductivity of the core-shell nanocomposites was influenced by polymerization time, current as well as the concentration of ions. The obtained excellent conductivity appeared with the current of 0.6 mA and the duration time of 1 h. In addition, the corresponding enhanced electrochemical performance of polypyrrole grown on graphitized diamond substrate is demonstrated compared with pristine polypyrrole. The morphologies of the obtained composites were illuminated through scanning electron microscopy (SEM) and the conductivity was demonstrated by electrochemical impedance spectroscopy (EIS). The characteristic peaks of polypyrrole and qualitative analysis of surface elements have been investigated by Raman spectra and X-ray photoelectron spectroscopy (XPS). The present research could demonstrate a new aspiration for the design and preparation of novel polypyrrole core-shell composites materials.