Large-scale, high-purity and uniform silver orthophosphate (Ag3PO4) nanowires had been synthesized by a facile hydrothermal method without employing any surfactants or templates for the first time. The nanowires were single-crystalline with lengths up to several micrometers. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and high-resolution transmission electron microscopy were used to characterize the morphology and structure of the as-prepared products. The as-prepared Ag3PO4 nanowires exhibited linear current-voltage (I-V) characteristics and excellent photoresponse. As the light was switched on and off, the currents could be reversibly switched between high and low value at the voltage of 0.1 V, which will find wide application in optoelectronic nanodevices.