Developing low-cost and high-performance catalysts for oxygen reduction reaction (ORR) is critical for fuel cell applications. In this study, hollow carbon nano-spheres (HCNS) are synthesized by a hydrothermal method and used as the support for silver nano-particles (Ag@HCNS) as the ORR catalyst. The morphology of Ag@HCNS is investigated by the transmission electron microscopy (TEM), scanning electron microscopy (SEM) and other methodologies. Results show that the silver nanoparticles with a diameter from 3 to 6 nm are evenly distributed on the surface of HCNS. The catalytic performances of the HCNS and Ag@HCNS for ORR are investigated by cyclic voltammetry, linear sweeping voltammetry, rotating disc and rotating ring disc electrode tests. The synergistic effect between HCNS and Ag nanoparticles plays the major role on the high catalytic activity of Ag@HCNS for ORR. The onset potential of Ag@HCNS (0.82 V v.s. RHE) catalyzed ORR is close to that of Pt/C catalyst. In addition, the reaction kinetics study shows that the Ag@HCNS catalyzed ORR major proceeds through 4-electron style. This paper promotes the understanding of the happening mechanism of ORR on the surface of novel carbon supported metal nanoparticles.