Abstract: Based on the data of tropical cyclones in the Northwest Pacific from 1949 to 2016, the tropical cyclones with sudden increase in the central intensity in Chinese offshore waters in strong El Nino years are selected. The atmospheric heat source and water vapor source from 1949 to 2016 are calculated and analyzed by using the back calculation method. It is found that the vertical heating rate of atmospheric heat source in the middle and lower troposphere increases, which is conducive to the enhancement of tropical cyclone. The vertical heating rate of water vapor source is low, and there is no obvious promotion relationship for the sudden enhancement of typhoon. The heating rate 6 hours before typhoon enhancement provides heat support for typhoon enhancement. Some typhoons will still enhance 6 hours after typhoon enhancement, and the heating rate of the whole region will also increase accordingly, providing heat for subsequent typhoon enhancement.