Organic-inorganic hybrid perovskite is a promising new generation of photodetection materials due to its advantages of direct bandgap, high absorption coefficient, and high carrier mobility. Researches have shown that the perovskite nanomaterials have various morphologies, such as quantum dots, nanowires, nanorods, and nanosheets. In particular the anisotropic nanowires photogenerated carriers transmit efficiently along the axial direction, which enhances the charge extraction efficiency of the photodetector. In this paper, the perovskite nanowire arrays were prepared by the self-assembly growth method. When the mass fraction of precursor solution decreased from 10% to 0.2%, the diameter of nanowires was reduced from micron to hundred nanometer scale. A photodetector based on nanowire arrays obtained from 0.5% precursor solution was reported. The light-to-dark response ratio of the device was as high as 3.7×104, the external quantum efficiency reached up to 180.88%, and the dark current density was as low as 1 pA. All data were measured under 2 V bias voltage and 660 nm red light. The remarkable improvement of the photodetector performance is attributed to the radial uniform distribution of the nanowires and high crystallization quality.