The photocatalytic hydrogen production has become one of the most promising strategies to solve the energy crisis and environmental pollution. Novel CdSe/SrTiO3 nanocomposites (average diameter 114.6 nm) with high photocatalytic activity are synthesized and used for visible light photocatalytic water splitting for hydrogen production. Through optimizing the concentration of CdSe QDs, CdSe/SrTiO3 nanocomposites exhibit increased visible light absorption and enhanced photocatalytic hydrogen evolution efficiency compared to SrTiO3 nanoparticles. The maximum H-2 evolution amount reaches to 3350.53 mu mol in 8 h by using CdSe/SrTiO3-3 as catalyst. Owing to the formation of heterojunction at the interface between CdSe and SrTiO3, the electrochemical impedance spectrum of CdSe/SrTiO3-3 exhibits the smallest arc radius and the photocurrent density of CdSe/ SrTiO3-3 reaches to 0.26 mu A cm(-2). The photogenerated electrons are effectively separated and transferred and the recombination of electron-hole pairs is avoided, thus significantly improving the photocatalytic hydrogen production performance of CdSe/SrTiO3 nanocomposites.