By using differential method, the inter-band chromatic aberration and intra-band chromatic aberration conditions in optical system were introduced, and the extended complex chromatic aberration theory was established. By comparing the refractive vs chromatic coefficients of each band and the whole band, the material was matched and iteratively optimized to correct all kinds of aberrations. Several ways of realizing the multi-band common aperture (MCA) optical system were discussed, including the medium-wave (MW)/near-infrared (NIR) secondary imaging system with transmission structure, which was introduced into the respective detectors by the dichroic beam splitter in convergent optical path; the MW/long-wave (LW) infrared secondary imaging system with transmission structure, which adopted the co-focal surface design of the co-optical road; and the AN/AAQ-33 “Sniper XR” pod’s main optical system, which adopted MW/NIR co-aperture transmission fore telescope system; the AN/ASQ-228 ATFLIR pod’s main optical system, which adopted the MCA off-axis three-mirror anastigmatic (TMA) fore telescope system; the AN/AAS-52 MTS-B pod’s main optical system, which adopted the MCA coaxial bias field of view (FOV) TMA fore telescope system; the EKV’s main optical system, which adopted the MCA coaxial four mirror secondary imaging system. And correspondingly, some coaxial mirror-lens fore telescope systems were introduced, and the last, some typical missile borne MCA imaging optical structures were introduced.