Abstract:Based on the model of infrared radiation of seawater, the factors which included emissivity of sea surface, radiation of sky, shadow coefficient, atmosphere were considered, and the directional radiant power of thermal wake of the submarine at 8~ 14μm was also calculated. According to the difference in temperature between thermal wake and seawater, the operation range of the detector to thermal wake was calculated. And it was gotten that the radioactive characterization related to direction of detector, wind speed, temperature of wake, temperature of atmosphere and so on. Used the infrared thermal image system whose temperature resolving is 0.001℃, the detection range, discrimination range, recognition range of the detector to thermal wake were 8.84km, 3.88km, 2.74km with the difference in temperature between thermal wake and seawater was 0.02℃.