Abstract: A novel Sm³⁺-SrTiO₃/TiO₂ composite nanofibers were synthesized by one-step hydrothermal technique. By this way, TiO₂ nanofibers could serve as the both substrate and reactant. Moreover, not only doping of Sm³⁺ into SrTiO₃ but also in-situ growth of SrTiO₃ on skeleton of TiO₂ could be simultaneously satisfied. The as-synthesized Sm³⁺-SrTiO₃/TiO₂ composite nanofibers were characterized by XRD, XPS, FESEM and HRTEM. The photocatalytic activity was evaluated by the degradation of rhodamine B and p-chloro phenol. The results show that rare earth Sm³⁺ ions are doped into the SrTiO₃ lattice and replace Sr²⁺ in SrTiO₃, forming an impurity level in forbidden band. The range of the light absorption by SrTiO₃ is enlarged. Meanwhile, the defects are introduced into SrTiO₃ lattice, acting as trapping cites of photogenerated electrons and hence reducing the recombination of charge carrier. The additionally, the heterojunction between SrTiO₃ and TiO₂ is beneficial for the electronic-hole separation. With these regards, Sm³⁺ doped SrTiO₃/TiO₂ composite nanofibers exhibit highly photocatalytic activity under visible light.