Magnetic hollow MnFe2O4 nanoparticles were prepared by hydrothermal method and the nanoparticles surface were modified by(3-aminopropyl) triethoxysilane(APTES), then absorbed silver ions. After reduction the magnetic MnFe2O4/Ag composite nanoparticles were successfully prepared. The X-ray diffraction, transmission electron microscopy, magnetometer and ultraviolet spectrometer were applied to characterize the samples. Inhibition zone method was used to detect the antimicrobial effect of MnFe2O4/Ag composite particles. The characterization and detection results showed that the parent hollow magnetic MnFe2O4 was not active in antimicrobial property, and the inhibition zone radius of the composite MnFe2O4/Ag to E.coli was 1.78 cm and that to S. aureus was 2.14 cm. The MnFe2O4/Ag antibacterial durability test results showed that Ag-carrying magnetic composite particles had high stable and lasting antibacterial performance.