Abstract: The development of ultraviolet warning and its key device is introduced, including the characteristics and development of ultraviolet warning, ultraviolet radiation transmittance and the development of ultraviolet detector. A new vacuum ultraviolet detector is described, its photocathode is a solar-blind, a proximity focus tube with less dispersion and image distortion is adopted, its read-out system has light-coupling and electricity-coupling, the light-coupling read-out system is simpler and responds in real time, the electricity-coupling read-out has high sensitivity and resolution as well as long detection distance. Auto gating BSP power supply is adopted to extend dynamic range, protect photocathode and microchannel plate.