In common perovskite solar cells utilizing TiO2 as electron transport layer, undesirable charge recombination at TiO2/CH3NH3PbI3 interface is one of the crucial issues to the photovoltaic performance of the device. Moreover, exposure of TiO2 under long-term solar illumination may also cause deep trap states at TiO2 surface and seriously influence the device stability. Herein, we introduce an insulating ultra-thin Al2O3 interfacial layer between the mesoporous TiO2 film and perovskite layer. The power conversion efficiency of the solar cells fabricated via spray deposition in the air increased from 9.36% (V-oc= 0.86 V, J(sc)= 17.21 mA cm(-2), FF=0.63) to 12.79% (V-oc = 0.93 V, J(sc) = 21.56 mA cm(-2), FF = 0.64). The significantly improved photovoltaic performance is mainly attributed to the efficient reduction of charge recombination. Meanwhile, the Al2O3-modified perovskite solar cells exhibit a strong stability under long-term light exposure compared with the common device without the Al2O3 interfacial layer.