An ICMOS is fabricated by directly coupling the output window of the image intensifier with a CMOS resulting in the characteristics of high sensitivity, fast response, and adjustable spectral range. In this study, the influence of the cathode, microchannel plate, phosphor screen, CMOS, and other components on the imaging performance of direct-coupled ICMOS are analyzed according to the composition of ICMOS, thereby proposing the principle for selecting the image intensifier and CMOS for ICMOS. The advantages of image intensifier manufacturing combined with the actual low-light imaging performance of directcoupling ICMOS are verified on an 18 mm NVT-7 image intensifier and 1-inch CMOS. The results show that the ICMOS camera can be used under 5×10-4 lx light conditions with a resolution of 16 lp/mm. In addition, the gain of the image intensifier for ICMOS should not exceed 4000 cd/(m2?lx), and the output brightness of the phosphor screen has minimal effect on performance under the condition of an appropriate gain.