Magnetic mesoporous gamma-Fe2O3@Ti0.9Si0.1O2 (abbreviated as Fe@TiSi) core-shell nanofibers were prepared using sol-gel chemistry combined with coaxial-electrospinning technology by adjusting the inner and outer feed ratios. The properties of these novel core-shell nanofibers were characterized by SEM, HRTEM, XRD, FTIR, BET, XPS, and UV-vis spectra. To evaluate the chemical properties of the nanofibers for cleaning typical organic wastewater, methylene blue (MB) was used as a target organic pollutant and was cleaned under irradiation with sunlight and visible light. The Fe@TiSi hierarchical nanofibers composed of a 1:10 feed ratio displayed a mesoporous structure and showed the highest photocatalytic activity for the degradation of MB in water. Furthermore, 86.8% and 71.1% of the MB, which was added at an original concentration of 1 mg/L, was removed after 60 min of irradiation with sunlight and visible light in the presence of Fe@TiSi at a concentration of 0.2 g/L, and 100% of the MB was removed after 75 min. It is very important that the magnetic nanofibers could be recycled rapidly with an outside magnet, and the actual water treatment process was easy to achieve. Moreover, the mechanism of MB degradation by Fe@TiSi core-shell nanofibers was proposed.