The invention provides a polymer solar battery with an inverted structure. According to the polymer solar battery, an laminated structure is composed of a glass substrate, an indium tin oxide (ITO) transparent conducting film, an electron transporting layer, an interface modification layer, an organic active layer and an MoO3 / Ag composite electrode in sequence, wherein the electron transporting layer is a zinc aluminum oxide (ZAO) thin film, the interface modification layer is a polyvinylpyrrolidone thin film, and the organic active layer is a poly-3-hexyl thiophene-fullerene derivative thin film. The polymer solar battery with the inverted structure has the advantages that polyvinylpyrrolidone is used as the interface modification layer, so that materials of the organic active layer make tight contact with materials of the inorganic electron transporting layer, the series resistance of a device can be effectively reduced, the parallel resistance of the device can be effectively increased, charge carriers are effectively collected, carrier recombination is reduced, the number of fill factors of the battery is obviously increased, and energy conversion efficiency of the battery is obviously improved; on the premise of not increasing cost, large-area commercial production can be facilitated, the industrialization process of the polymer solar battery is accelerated, and social demands are met.