Granular (FePt)100-x–(NiO)x nanocomposite thin films with x in the range of 0 – 42 vol.% were fabricated on a natural-oxidized Si(100) substrate. It is found that both the coercivity and FePt domain size decrease with increasing NiO content for the (FePt)100-x–(NiO)x films. When the FePt-NiO nanocomposite film with NiO content of 10.4 vol.% is post-annealed at 750 °C with a high heating ramp rate of 100 °C/sec, the in-plane coercivity (Hc//) and perpendicular coercivity (Hc⊥) of the FePt films are 6.4 and 5.5 kOe, respectively. On the other hand, we used conductive atomic force microscope (CAFM) to confirm that the NiO compound is distributed at grain boundary of FePt grain that will constrain the domain size of FePt and obtain isolated magnetic domains. These results indicate that NiO addition is beneficial to enhance recoding density and reduce media noise of the FePt magnetic film.