The surfaces of carbon black were modified by nitric acid oxidation. The surface structures of the original and oxidized carbon black were investigated by means of FT-IR and XPS, respectively. Furthermore, the oxidized carbon black and distilled water were mixed to form the self-dispersal nanometer carbon black pigment. The particle size distribution and dispersion stability of the carbon black pigment were investigated by means of particle-size analyzer and spectrometer, respectively. The results showed that some highly marked hydrophilic character functional groups on carbon black surfaces were increased greatly by nitric acid oxidation.