Abstract: The space atomic oxygen is an important issue in the space environment. The future AO detection technique requires a light weight and a reduced power consumption of the related AO sensors, to allow for the in-situ measurement of the space AO fluence. Based on the analysis of major AO detection methods and their characteristics, a technique using the carbon nanotube gas sensor is proposed for the low-content atmosphere detection. The sensor features the small size, the low power consumption, the high sensitivity and the quick response, which can work continuously and repeatedly, represents an important direction for nano sensors, and could be used for the AO fluence measurement to improve the technical level of China's AO detection.