In order to meet the requirements of spacecrafts for autonomous navigation systems with light small,cheap and reliable performance,a wide-angle static infrared horizontal system was designed.The system chose the operating wavelength range of 14 to 16.25 μm to keep a stable radiation,and its full field of view was set as 136° and F number as 0.61.By using a retrofocus structure in image space,the back working distance has been 15 mm in the optical system.On the basis of the design principle of a f-θ lens, the aspheric surface was used to rationally optimize the wide-angle system,then the related error of linear characteristics of the f-θ len is less than 0.5%,and the modulated transfer function is higher than 0.6 at 15 lp/mm in the image plane(approaches diffraction limit).In a circle with radius of 20 μm,the radial energy is higher than 85%.Furthermore,a telecentric optical path was used in the system,which improves the relative illumination to more than 99%.These results show that the designed lens has the advantages of simplicity,compactness and long back working distance,and can balance the correctness of off-axis aberrations.