In this study, magnetic nanoparticles were prepared by the arc plasma deposition (APD). The monodisperse Fe-Pt nanoparticles (5~10 nm) were obtained on the surface of SiO2 nanoparticles. Deposition voltage and shot counts can control particle size of Fe-Pt. The coercivity of Fe-Pt/SiO2 composite particles increased after annealing at 300°C, and the maximum coercivity value reached to 583 kA·m−1. In the selected area diffraction pattern obtained by transmission electron microscopy (TEM), amount of the order L10 phase was increased by annealing at 300°C. The Mn-Bi nanoparticles (5~20 nm) were also prepared by APD. The Mn-Bi was deposited on Fe nanoparticles, which were prepared by hydrogen-plasma-meta-reaction (HPMR) method, and monodisperse Mn-Bi particles were obtained on the Fe nanoparticles. Consequently, the arc plasma deposition is effective process to prepare composite magnetic nanoparticles.