中文摘要：

利用1958-2009年中国北方243个测站逐月降水资料，采用聚类分析和旋转经验正交展开方法，从年变化和年际变化的尺度，对中国北方降水进行了分区研究。按照降水年变化的相似性，将北方分成了7个区。除了个别测站年降水有两个峰值期，北方大部分地区的降水年变化特征都比较相似，降水主要集中在夏季。按照降水年际变化的相似性，对北方地区进行了四级分区，一级分区分成2个区，二级分区分为4个区，三级分区分为9个区，四级分区分为12个区。近52年来，北方中东部区年降水量呈下降趋势，而西部区呈上升趋势。降水年际变化的分区格局在20世纪80年代发生转折，在60、70年代，北方降水主要呈三区格局，东部与西部降水的年际变化比较相似，与中部差异大；进入80年代之后，呈两区格局，东西差异显著。

英文摘要：

The study of division, according to the annual and interannual variations, is separately car- ried out by using the cluster analysis and REOF analysis methods based on the monthly precipitation data at 243 stations in Northern China during 1958-2009. According to the correspondence of changes of monthly precipitation, Northern China can be divided into seven regions. The study result shows that ex- cept for a few stations where there are two peaks of precipitation within one year, the characteristics of an- nual precipitation around the most areas of Northern China are similar, which precipitation in summer is much more than that in other seasons. With the same methods, the four-level divisions of annual precipi- tation are obtained： 2, 4, 9 and 12 regions. In recent 52 years, the precipitation trend appeared downward in the eastern and central part of Northern China, while it increased in the west one. The division pattern of annual precipitation experienced a change in the 1980rs. From 1960＇s to 1970＇s, there are three regions. The east region and the west are more likely, distinguished from the central region. However, there were two regions since 1980＇s, which represented the remarkable differences between the east region and the west.