A study of detecting the sea fog from NOAA-16, and -17 Advanced Very High Resolution Radiometers (AVHRR3) is presented. Sea fog occurs frequently over China Sea at different season, especially on spring, and forms an obstacle for sea traffic. In this paper, several sea fog events are selected, analyzed and compared; their radiance and texture characterization with other bodies from satellite observations is given. Firstly, It is found that the satellite measured reflectance of channel 3a (1.58-1.64μm) is between the channel 1(0.58-0.68μm) and channel 2(0.725-1.0μm), and the one of channel 2 is lowest, which is different from the ocean, the land and some cloud body. Those results are explained with Mie scatter theory. Secondly, the sea fog, which is the cloud clung the earth surface, is generally characterized by higher reflectance than the surrounding water in visible, while it is similar to the surrounding in the infrared radiance brightness temperature. According those different feathers, a parameter, which is the standard deviation of the reflectance (or brightness temperature) differences between the adjacent eight pixels and the one, is defined as the texture to detect the marine fog. Thirdly, the sea fog is often coherent and continuous in spatial. It could be used to modify and restore some misjudge point or segment. Based on those analyses, finally, we design an algorithm for detect the sea fog at day. The results show that this method is valid to extract the fog region from NOAA/AVHRR3.