Variable F/number-cooled infrared detectors, which are based on variable cold aperture technology, are urgently needed because they can improve the performance of zoom infrared optical systems and consider both spatial resolution and sensitivity. Compared with the traditional zoom infrared optical system, the variable F/number zoom infrared optical system can balance the resolution and sensitivity when the system switches between large and minimum scales. Furthermore, the variable F/number zoom infrared optical system can improve the aperture utilization rate of the optical system and reduce its radial dimensions, which is beneficial for improving the imaging quality and miniaturization design of the infrared optical system. In this paper, we discuss the relationship between the variable F/number and zoom and summarize the research progress in the field of variable cold-aperture infrared detectors. Finally, we analyze the key technical challenges of the mainstream technology approach.