ZnO nanorods arrays, with high crystal quality has been successfully synthesized by sol-gel assisted hydrothermal method and their photoelectric property has been studied for toward a UV detection. The results show that the diameter of nanorods with high crystal quality samples becomes thinner from the bottom to the top, and the middle diameter of that is 120 nm. In addition, the photoelectric performance of ZnO nanorods arrays shows that the dark current of the sample shows the phenomenon of forward conduction and reverse cutoff, indicating that the sample has good heterogeneous p-n junction between the n-type ZnO nanorods arrays and p-type Si substrate. The dark current of the ZnO nanorods arrays photoelectric device is 4.89 µA, the photocurrent of that is 996.33 µA, and its photoelectric sensitivity of that is 203.7. The photoelectric performance shows the potential application of ZnO nanorods arrays for nanoscale UV photodetector.