Highly efficient all-inorganic CsPbI2Br perovskite solar cells (PSCs) are fabricated by employing a simply solution processed ZnO/SnO2 bilayer electron transport layer (ETL). High iodine content CsPbI2Br film forms on the bilayer ETL surface with regular crystal grain and full coverage, which is benefit from the well crystal matching between perovskite and SnO2. On the other hand, the lower work function of ZnO compared with SnO2 reduces the energy losses (E-loss) in devices. As a result, the all-inorganic CsPbI2Br PSCs based on ZnO/SnO2 bilayer ETL demonstrate high V-oc of 1.22 V and improved power conversion efficiency (PCE) to 13.7%.