Micro-satellite was greatly developed in the past 20 years due to its advantages of small-size, light weight, short developing period, low cost, etc. Now, micro-satellite plays a great role in many realms, such as navigation, communication, earth observation, science research and technology experiments, which make it to be an important part of space technology. To miniaturize, micro-satellite has to be equipped with small-size instruments. A small-sized camera worked in visible band was introduced, which can be installed on micro-satellite. Technical parameters of the camera were as follows： effective focal length was 210 mm, optical aperture was 56 mm, spatial resolution was 33 μrad, field of view was 7.8°×7.8°, or 16 M pixels in all. In the design phase, different optical structures were compared, and a catadioptric system was adopt. Fused silica and low density flint glass materials were used to balance chromatic aberration. Total length of optical system was 110 mm, and the ratio between total length and effective focal length was less than 0.53. The weight of all lenses was under 370 g.