Fe3O4/TiO2 nanofibers were prepared via electrospinning technique. Then, the samples were modified with Ag nanoparticles by hydrothermal method to obtain the composite fibers with strong magnetism and excellent photocatalytic efficiency. XRD, SEM, TEM and UV-Vis adsorption spectra were used to characterize and analyze the structure and morphology. The photocatalytic efficiency was tested under ultraviolet light irradiation using Rh B degradation as the model reaction. The results showed that TiO2 in all samples were anatases and Ag nanoparticles were scattered on the magnetic TiO2 fiber surface averagely. The UV-Vis spectra showed that TiO2 photoadsoption ability enhanced and the adsorption range were shifted to the visible light region. After modification with Ag nanoparticles, the photocatalytic efficiency of Rh B degradation rate can reach 99. 5% under 40 min UV light irradiation. The new material with strong magnetism can be separated easily and cyclically used by adding the magnetic field.