Using the rotated empirical orthogonal function (REOF) method,the normalized rainfall field during the May to July period in the Jianghuai Valley is divided objectively into the north and south regions.Based on this,the long-term trend and periodic variations of each region rainfall anomalies are analyzed.It is found that in the Jianghuai Valley,the peaks of precipitation anomalies in the south and north regions appear separately in June and July respectively.The trend of variations in the south region of the Jianghuai Valley is obvious in comparison with that in the north region,but the two regions have remarkable characteristics of interannual and interdecadal changes in the recent 50 years;There mainly exist 3-year interannual periods both in the south and north regions and a 21-year interdecadal period in the south region and a 15-year interdecadal period in the north region.Precipitation departures during the May to July period in the Jianghuai Valley is in phase with those in many areas of China in the wet and dry years,but the precipitation departure in the north region is always out of phase with that in south China.Further more,the rainfall anomaly in the Jianghuai Valley is directly influenced by the variations of the latitude of the subtropical high ridge and the intensity of the subtropical monsoon system.