Dual-band and multi-band imaging techniques get more and more attention of the national military. As a key part, dual-band optical systems, especially visible light/long-wave infrared (VIS/LWIR) wide-band imaging systems, become the focus of research. The dual-band imaging systems for several major structural forms, including reflective, catadioptric and refraction forms are analysed, and the composition and characteristics of the refraction form are introduced. For the shortcomings of the dual-band system, a VIS/LWIR common-window objective lens in the refraction form used in handheld field is designed. The system′s main technical indicators are: 0.6~0.8 μm (VIS), 8~12 μm (LWIR), VIS=47 mm，IR=58 mm, 2ω=9.8°, FVIS=2, FIR=1.3. Design results meet all the indicators, and the image quality meets the requirements in both bands. The size of the entire optical system is about 51 mm×93 mm×136 mm, which is compact and practical.