Polymer photodetectors have been paid much attention in the field of wearable sensing devices and solar cells, due to their excellent performance. In this work, self-powered n-Zinc Oxide/p-Poly(3-hexylthiophene) (n-ZnO/p-P3HT) inorganic-organic hybrid heterojunction photodetectors were successfully fabricated. The polymer P3HT as active layer can efficiently response for visible light. The n-ZnO as light scattering and electron transport layer was composited by 1D-ZnO nanorod arrays (NRAs) and 0D-ZnO quantum dots (QDs) hybridization structure. Compared with the reference device of ZnO NRAs/P3HT, the ZnO NRAs/6 Layers ZnO QDs/P3HT device achieves the best performance, and it shows a photo-to-dark current ratio of 9058, a responsivity of 15 mA/W and a normalized detection of 2.08 × 1011 Jones under 440 nm light illumination and zero-voltage bias. The present work provides a new way to optimize the performance of polymer photodetectors.