Abstract: A visible infrared integrated optical system of a large field of view is designed by using optical software, and the FOVs of the visible system and infrared system are 5.2 degrees and 5.12 degrees respectively. The orbit of the system is 675 kilometers, and have a large width of 61.3 kilometers and 60.36 kilometers respectively can be observed. The system uses a partial field to separate the field of visible light and infrared light respectively, and realize dual optical paths, dual bands and double fields of view imaging at the same time, which improve utility of visible light and infrared light by avoid the use of dividing light elements. Visible light system selects a three mirror system with a focal length of 9 000 mm. The infrared system uses two three mirror systems with a total focal length of 2 025 mm, and the entrance pupil of the rear system has the same position and size with the exit pupil of the former system. After optimizing, the modulation transfer function of the visible system is more than 0.45 at 50 lp/mm, and the infrared system's modulation transfer function is above 0.65 at 25 lp/mm respectively. The imaging quality of both systems reaches the diffraction limit.