Organic-inorganic lead halide perovskite materials have attracted wide attention owing to their great optoelectronic properties and low-temperature solution processability. Mesostructured perovskite solar cells (PSCs) could help to further improve the photovoltaic property. However, the existing approaches by inserting a layer of metal-oxide are generally need special treatment and consume much energy. In this work, an Ar plasma etching method is employed to modify composition of the perovskite absorb material with its morphology remain unchanged, which can effectively avoid unfavorable defects and enhance the charge separation efficiency. Based on controllable pore structure and porosity, the idiosyncratic mesostructured perovskite solar cells yield an 18.7% improvement in power conversion efficiency as compared with the common planar-type counterparts. Therefore, this method offers a room temperature scheme for high-performance mesostructured perovskite solar cells, making the flexible PSC possible.