Abstract: The basins of middle reaches of the Yangtze River are the worst flood area of whole basin. To study the variation regulation of the floods in this area and EI Nino events over a long historical period and to identify the teleconnection between them assure improvement in predictions of floods in the region. By using statistics analysis, both time series of the floods and EI Nino events since 1525 are studied. The results show that the main cycle of flood variation is longer than that of EI Nino events. The latter obviously shows the fluctuations of about 2year and 3～4 year period while the former is not so significant but can also be identified obviously the period of 2, 8 and 40 years (at least exceeding the level of confidence 0.03). By further analyzing the coupling fluctuation of the two time series, the significant teleconnections between them at both high and moderate frequency sections are found. The result turns out that the response of the floods along the middle reaches of the Yangtze River to the effects of El Nino events is not only immediately delay (see one year) as many Chinese scientists believe, but also can be somewhat longlived (as long as about 8 years). The results also explicate that the shorter the interval of EI Nino events, the sooner the following flood responds. Vice versa, flood could delay if the interval time of EI Nino events is longer. 

Key words: historical floods in the middle reaches of the Yangtze River, EI Nino events, teleconnection