The PCS/TiO2 fiber mat was fabricated from polycarbosilane (PCS) and titanium (IV) butoxide using an electrospinning technique. The fiber mat was irradiated with an electron beam to induce structural crosslinking. Subsequently, the crosslinked PCS/TiO2 fiber mat was heat-treated at 1,300 ℃ in air. The PCS/TiO2 fiber mat was characterized with FE-SEM, EDX, XPS, XRD, TGA, and a Raman spectrum analysis. The heat-treated PCS/TiO2 fiber mat has an average diameter of 2 and a high specific surface area which was 22.35 m2/g .The surface of PCS/TiO2 fiber mat showed a newly interconnected worm-like substructure composed of TiO2 nanoparticles. The PCS/TiO2 fiber mat was evaluated for the photodecomposition of dye methylene blue under ultraviolet light. UV.vis result shows that about 90% of methylene blue was degraded after 2 h under UV light by PCS/TiO2 fiber mat. On the other hand, about 55% dye was degraded by TiO2 nanopowder.