Abstract: Dual-band/dual-channel imaging system can effectively improve the detection and identification capability for infrared camera. A dual-band catadioptric optical system was designed, in which the mid-wave band and long-wave band could image at the same time. The Cassegrain optics system is shared by two channels, the dichroic lens and independent relay lens are adopted, and by combining with the secondary imaging technology, 100% cold stop efficiency could be realized. The focal length for two channels is 800mm and the wavelengths are 3.7 m～4.8 m and 7.7 m～10.3 m, respectively,the relative aperture is 1/2.3 for mid-wave band and 1/2.8 for long-wave band with the field of view of 1.2. The modulation transfer functions of each band at respective fields are all near the diffractive limit, which satisfies the needs of practical applications.