Abstract: Radiation gain acting as the main performance parameter of the ultraviolet(UV) image intensifier determines the comprehensive performance of it，so a test intensifier was designed to measure the radiation gain in UV image intensifier,whose test range was 200 nm~400 nm, and there were 6 (1/8,1/4,1/2,1,2and 3) fields of view (FOVs) for choice .Referring to the image intensifier brightness gain measurement device, the testing system of radiation gain in UV image intensifier was designed. Based on the testing principle and method, the test software was designed. By changing the voltage of micro channel plate,the cathode voltage and screen voltage, the UV image intensifier was measured. The test results indicate that the test curve changing trend coincides with the operation characteristics of the UV intensifier, the incident UV radiation intensity is 10-7W/cm2~10-11W/cm2,the minimum detecting intensity of radiometer was 10-11W/cm2,the minimum brightness detection threshold is 310-4cd/m2 and the test repeatability of radiation gain is better than 8%.