Abstract: Ultraviolet image intensifier has a very broad application prospects in many fields, such as space optical detection, environmental monitoring, strategic defense, and so on. Signal-to-noise ratio measurement system of ultraviolet image intensifier was designed by reference to the test principle of signal-tonoise ratio for UV image intensifier, and its test conditions were provided. The relationship between voltage of MCP and signal-to-noise ratio of UV image intensifier was deeply studied, and its curve is measured by using the development of its own signal-to-noise ratio tester for UV image intensifier. The result shows that in the region of less than 850 V, the output of the signal-to-noise ratio of the ultraviolet image intensifier is increased with the increase of voltage; when the voltage is more than 850 V, the output of the signal-to-noise ratio of the ultraviolet image intensifier is essentially unchanged.