The natural hydrological rhythm has been altered under the combined effect of climate change and intensifying anthropocentric activities during the past decades at Poyang Lake, the largest freshwater lake in China. The main objective of this paper is to analyze the change process of water-levers at different time scales. In this research, the fluctuation characteristics of water-lever, such as monthly changing feature, annual variance tendency, extreme values, saltation feature and periodicity, were evaluated by using statistical analysis, trend analysis, Mann-Kendall non-parameters test and wavelet analysis methods based on the observed daily water-level time series from Hukou Station, Xingzi Station, Duchang Station, Wucheng Station, Tangyin Station and Kangshan Station at Poyang Lake. The main findings are shown as follows: the water-level drastically fluctuated during months and the highest water level (17.75m) and lowest water level (10.8 m) generally appeared in July and January, respectively, with an amplitude of 6.95 m; although the water-level presented a feeble downward trend during the past decades, a rapidly descending amplitude occurred after 2003, accompanying extremely low water level situation; there are three obvious saltation points at 1955, 1965 and 2006, and the maximum water-level variation is close to 2 m; periodicity, effected by many factors, is inconspicuous only with a weak periodic in 28 time scale. Results of this study demonstrate the change situations of water-level at Poyang Lake in annual and inter-annual, which will provide instruction for water security associated with flood control, drinking water usage and water ecology in the lake basin. Furthermore, the results can be applied as a foundation for drawing scheduling rules of reservoirs.