The Cs-doped ZnO nanorod array (CZO-NRA) is fabricated by using the chemical bath deposition technique, which is used as the electron transporting layer (ETL). The mixed solution of ethanolamine and 2-methoxyethanol is used to modify the surface of CZO-NRA, and an inverted polymer solar cell (IPSC) is fabricated. The research results show that, the moderate Cs-doping increases the preferred orientation degree of crystallinity along the c-axis for the nanorod, decreases the deep level defect in ETL induced by the oxygen vacancies and the interstitial Zn atoms, decreases the series resistance of devices, and increases the short-circuit current and the filling factor of devices. The surface modification reduces the surface defects, decreases the contact resistance between ETL and the active layer, and suppresses the interfacial carrier recombination. Compared with that of the undoped devices, the power conversion efficiency of the surface-modified CZO-NRA devices is increased from 1.27% to 2.89%.