Using the historical materials of 5 sites on drought and flood in the region of Poyang lake basin and the surrounding area from 1467 to 2016, combined with data from China recent five hundred years of drought and flood atlas and modern precipitation data, the drought and flood series had been reconstructed based on the correlation coefficient weighted method. Spatiotemporal variation of drought and flood series in the Poyang lake basin in recent 550 years were analyzed by means of Ensemble Empirical Mode Decomposition and Empirical Orthogonal Function. The results show (1) the changes of the IMF components in the Poyang lake basin are in line with the characteristics of the nonlinear changes of natural signals, and the main highfrequency change period is 2-3 a, 7-8 a; the middle and low frequency cycle is 22 a, 36 a; the low frequency cycle is 110 a, 220 a and so on. (2) The EOF decomposition of the spatial field of the drought and flood series shows that the cumulative variance contribution of the first four modes is 93.68% and the convergence effect is obvious. The first mode is the whole region has the same drought or flood state. The second and third modes represent the inconsistency of drought and flood in northsouth direction and eastwest direction. The fourth model represents the extreme precipitation type in South Jiangxi province. (3) The results of the power spectrum analysis of the time series of main spatial modes show that the change period of the spatial pattern of drought and flood is consistent with the EEMD decomposition of drought and flood series.

Key words：EEMD; EOF; drought and flood variations; spatiotemporal variation; the Poyang lake basin