Formation of heterostructure and nanostructure is promising approach to improving the photocatalytic activity of TiO based photocatalysts. In this work, MoS@TiO@poly(methyl methacrylate) (PMMA) was prepared by freeze drying of hydrothermally treated electrospun PMMA nanofibers containing titanium n-butoxide and MoS nanosheets. As-prepared nanocomposite revealed a 3D nanofiber network structure with high specific surface (83.6 m/g), in which MoS nanosheets loaded with TiO nanoparticles were distributed on the surface of PMMA fibers. MoS@TiO@PMMA showed better photocatalytic performance than MoS@PMMA, TiO@PMMA, MoS@TiO and MoS@P25@PMMA towards the photodegradation of methyl orange (MO) under UV illumination. Typically, MoS@TiO@PMMA (100 mg) could degrade MO (10 mg/L, 100 mL) completely in 40 min under UV irradiation, revealing good photocatalytic activity. Moreover, the nanocomposite could be facilely recovered by filtration, and maintain almost the same photocatalytic activity after cycling tests for ten times, indicating excellent stability and recyclability. The enhanced photocatalytic performance of the nanocomposite might relate to the heterostructure between MoS and TiO to suppress the recombination of photo-induced charge, and the 3D hierarchical nanoweb structure to afford large specific surface area and high density of active sites.