Photoconductive metal-semiconductor-metal ultraviolet detectors were fabricated based on the polycrystalline MgZnO films, which were grown on SiO2/Si substrates by radio frequency magnetron sputtering. The peak response of the detector was at 300 nm, which lay in the solar-blind spectrum range (220 to 300 nm). And the peak responsivity was 34.02 A/W. The ratio of Iph/Id was as high as 2659.7 at 5 V bias under a low pressure Hg lamp illumination. And a rise time of 44.48 μs (90%) and fall time of 120.2 ms (10%) of the detector were acquired.