A novel magnetic nano-sorbent Fe3O4/Ag was synthesized and applied to capture the elemental mercury from the simulated flue gas. The morphology, components and crystal phase of the sorbents were characterized by transmission electron microscope (TEM), energy dispersive spectrometry (EDS) and X-ray diffraction (XRD), respectively. The mercury removal performance of the sorbents was investigated through the fixed-bed tests. The results indicated that silver was successfully loaded on the surface of Fe3O4 particles, which could significantly enhance the Hg0 removal performance of the sorbents. Flue gas components, including CO2, SO2, and NO, have little impact on the Hg0 removal performance of Fe3O4/Ag sorbents, while O2 has a slightly positive effect. The Hg0 removal efficiency decreased with the increasing of temperature, Hg0 inlet concentration and gas hourly space velocity. Only one broad mercury desorption peak at approximately 210 °C could be observed during the temperature-programmed desorption (TPD) process, which indicated that mercury species existing on the surface of Fe3O4/Ag sorbents might be elemental mercury instead of oxidized mercury. Furthermore, the reusability tests showed that the Fe3O4/Ag sorbents could be efficiently regenerated and reused. Finally, the theoretical analysis based on the DFT method showed that a weak chemisorption of Hg0 on Fe3O4 sorbents changed to a strong chemisorption when silver was loaded. The results of theoretical analysis conformed to the experiments results well.