TiO2 nano-structured fibers with trace Sn4 -doped (Sn4 /TiO2) were prepared via a dipping-thermal conversion method (called as two-steps method) by using absorbent cotton fiber as the template and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), resolution transmission electron microscopy (TEM), ultraviolet-visible spectroscopy (UV-Vis ) techniques. Under the irradiation of Hg and Xe lamps (Simulated sunlight), the degradation of methylene blue (MB) on the samples was used as the model reaction to investigate their photocatalytic property. The results show that Sn4 /TiO2 nano-structured fibers with trace Sn4 are prepared via the two-steps method, doped Sn4 ions are well-distributed in TiO2 lattice and make the absorption edge of TiO2 red-shift and remarkably increase the intensity of the light adsorption in the range of UV to visible. And under Hg and Xe lamps, as-prepared samples show good photocatalytic activity for the degradation of MB solution. It is important that the activity of the samples Sn4 /TiO2-0.030% is 4.5 times as TiO2 under Xe lamp (Simulated sunlight) but 2.7 times as TiO2 under Hg lamp (UV light). Good photocatalytic property of Sn4 /TiO2 can be ascribed to multi-structure and the increase of active centers of TiO2 material and doped energy level between valence and conduction bands of TiO2 due to doping Sn4 ions in TiO2. In addition, the photocatalytic degradation of MB solution follows first-order kinetic behavoir well on the samples.