Abstract: In order to improve the ability of target detection and recognition of the photoelectric detection equipment, a set of VIS/MWIR dual-band common-aperture optical system was designed. Based on the practical engineering experience, an optical design method with segmented design and combinatorial optimization was summarized, and the design process of the initial structure for the dual-band common-aperture optical system was reconstructed by reasonably distributing the focal power and selecting the appropriate initial structure. In addition, combined with CodeV and TracePro soft, the narcissus phenomenon of the refrigeration mid-wave infrared detection system was quantized, and the validity of the analysis conclusion was verified by the field test imaging. In the dual-band common-aperture optical system, the maximum field of view is 1.25°, and the distortion is less than 0.1%, which can work at ambient temperature −30℃～50℃. The 100% cold shield efficiency is realized by the mid-wave infrared detection system, and the switching of the size of the field of view is realized by the visible light detection system. The dual-band optical system has the functions of focusing and dimming, which shows good imaging quality, good processability, small assembly difficulty, and strong engineering implementability.