The power-spectral and maximum entropy-spectral analyses of the drought/flood data in the lower reaches of the Changjiang River have revealed the fluctuations of the cold/warmth south of the Huaihe River for the periods of 2—3, 5—6, 7—14, 17—20 and 27—32 years. It is evident by using the cross-spectral method that there is a significant correlation between the drought/flood and the cold/warmth. It is found that the evolution of the cold/warmth in winter is prior to the drought/flood in summer within the low-frequency range, but they are in phase within the middle-and high-frequency ranges.