基于海河平原28个四级子区1956年－2011年逐月平均降水量数据，运用线性倾向估计、Mann-Kendall趋势检验、Morlet小波分析等方法，对海河平原年降水量变化特征进行研究。结果表明：海河平原北部和南部降水最丰，中部滨海地区次之，而中部山前地带最寡；降水主要集中在夏季，约占全年降水量的68.7%，冬季降水量最少，约占全年降水量的2.5%。研究还发现，近56年来海河平原年降水量呈现不明显的下降趋势，这主要是由夏季降水量明显减少造成的。28个四级子区中，年降水量下降趋势较为显著的子区有12个，主要分布在黑龙港运东平原及西北部山前平原，而个别子区降水量变化呈现不明显的上升趋势。近56年，海河平原年降水量整体上的周期性变化不明显，但在1956年－1990年、1956年－1980年、1993年－2008年期间分别存在4 a、11 a和7 a尺度的周期变化。

Based on the average monthly precipitation data collected at 28 Level-4 sub-segments in the Haihe River Plain from 1956 to 2011, the variation characteristics of precipitation in the Haihe River Plain were analyzed using the methods of linear regression, Mann-Kendall trend test, and Morlet wavelets analysis method. The results showed that (1) the average precipitation in the Haihe River Plain varies spatially. The north and south have the most abundant rainfall, followed by the central coastal area, and the central piedmont has the least amount of rainfall; and (2) the average precipitation also varies temporally. Over 68.7% of the rainfall occurs in summer, while only about 2.5% occurs in winter. In addition, annual precipitation in the Haihe River Plain had an insignificant decreasing trend in the recent 56 years, which was caused by the obvious decreasing trend of precipitation in summer. Among the 28 Level-4 sub-segments, 12 of them showed a significant decreasing trend of precipitation, and they are mainly located in the Heilonggangyundong Plain and the piedmont plain in the northwest. Moreover, a few Level-4 sub-segments had an insignificant increasing trend of precipitation. In the recent 56 years, there was no significantly periodic change on the annual precipitation; however, there were a 4-year interval, a 7-year interval, and an 11-year interval occurring during the periods of 1956 to 1990, 1993 to 2011, and 1956 to 1980, respectively.