针对小波变换的不足之处,运用EMD方法对密云水库1956—2000年还原后的入库天然年径流量时序进行多时间尺度分析,发现其变化存在准2～4a、准5～6a、准8～9a、准11a和准17～19a的波动周期,并分析了各分量的趋势变化,对密云水库运行管理工作的科学化具有重要借鉴意义。 Aiming at the shortcomings of wavelet transform, the multi-time scale analysis of the natural annual runoff time after the reduction of Miyun Reservoir from 1956 to 2000 was carried out by using EMD method. It was found that there were quasi 2 ~ 4a, quasi 5 ~ 6a and quasi-8 ~ 9a, quasi-11a and quasi-17 ~ 19a cycles, and analyzed the trend changes of each component, which has important reference for the scientific management of Miyun reservoir operation.