Abstract: In order to study the effect of annealing process on the performance of planar inverted perovskite solar cells, high efficiency inverted perovskite solar cells in planar configuration are successfully fabricated. In devices, MAPbI_xCl_3-x is used as a photoactive layer, PEDOT: PSS is used as a hole transport layer, PC₆₁BM is used as a electron transport layer and BCP is used as a electron transportlayer. The effects of annealing time on the microstructure, crystallization and optical absorption properties of perovskite films were studied systematically. The effect of annealing processes on the performance of perovskite solar cells was investigated. It is found that the optimized annealing time is 5 min for perovskite thin films with high smoothness, crystallinity and absorption. Based on the optimized perovskite films, the highest power conversion efficiency of inverted perovskite solar cells in planar configuration is improved up to 15.79%. In addition, this type of device also shows excellent stability performance and low hysteresis.