Abstract: Thermal dynamic model of the tropical cyclone wassuggested in the paper. With the model, the thermal dynamic characteristicsof the tropical cyclone were analyzed. It is found that the energy totropical cyclone was provided by the steams condense. The steam condensingcauses the forming of circle, which outputs the power of the tropicalcyclone. This circle efficiency reaches the maximum peak with itstemperature increase within a certain height range. If the bottomtemperature is constant, the circle efficiency increases to be the maximumand then falls down with the increase of the height when the saturationtemperature is lower. However, when the saturation temperature is higher,the circle efficiency increases constantly with the increase of the height.When the ambient temperature at the sea surface in the range of 33~34oC, the efficiency achieves the maximum of about 7.4%. While theoutput power of the typhoon increases at all times with the temperatureincreasing. This indicates that the frequency and strength of the typhoonwill accelerate with the ambient temperature.