Sequential spin-coating procedure is a widely adopted strategy to prepare CH3NH3PbI3 on mesostructured TiO2 electrode for organolead halide perovskite-based solar cells. However, this method suffers from the rough surface and excessively residual PbI2 in the resulting perovskite film, deteriorating the device performance seriously. Herein, a facial modified sequential solution deposition method, by introducing an as-prepared CH3NH3PbI3 and PbI2 film before the traditional two-step process, was proposed to fabricate the perovskite-based solar cell with smooth morphology and trace amount of remaining PbI2. The optimal as-prepared film introduced improves the efficiency of CH3NH3PbI3 solar cells from 9.11% to 11.16%. The enhancement of device performance can be attributed to the increased light absorption ability and decreased recombination rate of carriers in CH3NH3PbI3 absorber. (C) 2016 Elsevier B.V. All rights reserved.