In order to realize the detection of dark and weak target in space, the optical system of visible light detection camera with a large aperture is designed. Its effective focal length is 350 mm, F-number is 1/1.6, field of view is 3.2°, and working wavelength ranges from 450 to 950 nm. The structure of the visible light detection camera is described, and the structure form is determined to be Maksutov′s two reflection system whose primary and secondary mirrors are spherical. CODE-V optical design software was used to iptimize the optical system. The image quality evaluation and thermal analysis result are presented. The result shows that each field spot diagram is nearly circular, 80% energy encircled is within the spot diameter of 26 μm, maximum distortion is less than 0.05% and lateral color is less than 5 μm, which meet the requirement of detection.