A dual-band optical system with a long back working distance and limited far zoom is proposed and designed for visible light (486?656 nm) and near-infrared (900?1700 nm) to satisfy the urgent demand for multiband fluorescence imaging in biomedicine imaging research. A zoom structure suitable for the dual-band system is adopted to address technical problems such as the broad range of chromatic aberration variation and limited selection of component optical power caused by the dual-band long-back-working distance zoom system. The initial optical powers of four groups of zoom structures of the system are calculated. The feasibility of the initial structure of the zoom scheme is verified using the ideal paraxial plane. The independent aberration design is performed for each group element of the system. In the common optical path part, dual-band aberration is optimized. The rear group uses a splitter prism to separate the two bands. Different rear fixed groups are designed for dual bands to correct the residual aberration of the system, and dual-band imaging under the long back working distance is realized. The system exhibits good tolerance characteristics, the zoom curve is smooth without an inflection point, the image plane is stable during the zooming process, and the imaging quality is excellent.