Institute of Materials, Chinese Academy of Engineering Physics, Jiangyou 621908, P. R. China To improve the stability of organic-inorganic hybrid perovskite, cesium-containing methylammonium lead iodide perovskite have been synthesized by one-step solution deposition. With the increasing of Cs+ doping concentration, direct optical band gap of perovskite was increases, while defects and roughness of perovskite thin films were gradually augmented. A certain amount of Cs+ incorporated in perovskite absorb layer could improve power conversion efficiency through the enhancing of open circuit voltage and fill factor. However, excessive Cs+ doping concentration results in the reduced of short-circuit current and fill factor, which reduced power conversion efficiency. The optimized ratio 10% Cs+ doping achieved the highest power conversion efficiency (16.84%).