As a binary semiconductor, Sb2Se3 possesses appropriate band gap, high absorption coefficient and remarkable air and moisture stability, promising for light absorption material in a practical solar cell. This study demonstrates that interfacial enginnering of TiO2/Sb2Se3 by CdS is able to considerably enhance the photovoltaic performance in planar heterojunction solar cells. Mechanistic investigations show that the optimized energy alignment upon the introduction interfacial layer is responsible for the improved device performance. With this approach, Sb2Se3 based solar cell delivers a power conversion efficiency of 3.9% with a high current density of 27.2 mA cm(-2), which is the highest efficiency in solution processed Sb2Se3 solar cells. This research provides basic understanding regarding the interfacial engineering of Sb2Se3 solar cell and practical strategy for improving the device efficiency.