Abstract: Traditional resolution measurement of image intensifier is based on the observation of human eyes, but this method is dependent on individual observer and its veracity is not very high. In order to improve this situation, an automatic resolution method for 3rd image intensifier was devised. A scientific class CCD was used in the system, and the observation system is composed of the CCD and a computer. Resolution target image on the image intensifier fluorescence screen was acquired and sent to the computer to carry out image processing and software analysis. Then the resolution of 3rd image intensifier is obtained, and the result is compared with traditional one.