Dual-field scanning optical systems can search for and track targets across large airspaces and over long distances, maintain good image quality, and achieve registration and splicing of sequential images. They have broad application prospects in security, national defense, and other fields. To meet the requirements of high resolution, low cost, miniaturization, and lightweight design in infrared systems, a dual field fast scanning optical system was designed using CODE-V software based on a long wave, uncooled, large format focal plane array detector with a resolution of 1024×768 pixels. The system consists of a Kepler telescope group and a focusing lens group. It achieves dual-FOV zoom functionality through the axial movement of the zoom group. A scanning galvanometer in the telecentric optical path moves rapidly and reciprocally to compensate for target motion and expand the field-of-view angle. The influence of spatial vibration on imaging quality is analyzed by using the dynamic modulation transfer function method to ensure that there are no problems such as image blurring and trailing during the motion process. The optical system distortion is less than 0.5%, achieving high-precision image registration throughout the entire field of view and maintaining stable and clear imaging during scanning.