Helmet night vision systems are developed from single-band to multi-band image fusion. In this study, we analyzed the technical program and image registration accuracy based on low-light-level helmet observation and a hanging infrared night vision device. Optical simulation analysis was also conducted. First, we analyzed the working mode of the combination of hanging infrared night vision and low-light-level helmet, as well as the design scheme of image rotation and circular field of view. Second, according to the design index of hanging infrared night vision, optical simulation of an infrared lens and projection lens was carried out. Third, the image registration accuracy was analyzed from three viewpoints: suspension accuracy, optical axis consistency, and distortion. Finally, according to the simulation results and image registration accuracy analysis, a technical scheme based on low-light-level helmet observation and suspended infrared night vision is feasible and can achieve the targeted effect.