Image intensifiers, which are core imaging devices for low-light-level night-vision techniques, are used worldwide as advanced military night-vision devices. A method of directly comparing and analyzing the final output image characteristics of different image intensifiers is the most intuitive routine for assessing the image quality of image intensifiers. However, because image intensifiers are direct-view imaging devices, they face many challenges, such as field experimental set-up, synchronous image capturing, and adaption of image intensifiers with different types. Therefore, an image quality assessment method and image quality comparison system for image intensifiers were proposed. Dual-channel image intensifiers, a low-light-level CMOS and a laser rangefinder were integrated into the system; the main optical axis of each device was parallel. The images of the image intensifiers and CMOS were synchronously observed and captured. The system is compatible with different types of image intensifiers and power supply modes. The distance between the target and the system was also measured. Moreover, several no-reference image-quality-assessment metrics were integrated into the software to assist the observer in assessing the image quality of different image intensifiers. The actual field test results show that the proposed system is convenient and practical for comparing the quality of different imaging devices, and can facilitate optimization of the manufacture of image intensifiers, thereby promoting the development of low-light-level night-vision technology.