The push-broom infrared remote sensing imaging technology plays an important role in the high-resolution earth observation, but the internal development of infrared imaging technology is baffled by the technical level of long-linear array infrared detector. To achieve high-resolution push-broom infrared imaging, a method by the use of line-plane-switching infrared fiber bundle was proposed. In this method, the linear array end of the imaging fiber bundle was used as a long-linear array infrared detector and the plane array end of the bundle was coupled by a mature small infrared focal plane array with the single fiber corresponding to the pixel of the focal plane. The main problem of the design of the objective lens and coupling lens in the infrared fiber image transmission system was analyzed. And a system with an objective lens and an coupling lens was designed for a kind of fiber bundle which has 4 000×6 pixels on its entrance end and has 160×150 pixels on its exit end. The imaging performance of the objective lens and coupling lens were close to the diffraction limits while meeting special requirements of infrared fiber image transmission system. The presented design is a better reference for this kind of fiber image transmission system. The mean transfer function was introduced for evaluating the MTF of the overall optical system, and the simulation results show a good image quality.