By using the daily summer(JJA)precipitation data from 33 observational stations in the east of Northwest China from 1960 to 2004,and the reanalysis data of 500hPa height field from NCEP/NACAR,the total precipitation and rainless days are first calculated.According to their features of significant negative correlation,a homogeneous dry-moist index is defined,and then by EOF analysis,the anomaly evolution feature of drought-moist index fields is studied.in addition,the 500hPa height anomaly field compound analysis in drought and moist anomaly is conducted,and the results show that consistent anomaly feature is the main pattern of summer drought-moist index in the east of Northwest China.Drying tendency is significant in the east of Northwest China in recent 45a.In moist years,the main feature of synochronized 500hPa height field is that Xinjiang ridge is weak and East Asia trough is shallow,but in drought years its feature is reverse.The main feature of prophase(December)500hPa height field is that Ural ridge line is lean to west and East Asia trough is shallow in moist years,it is also reverse in drought years.The prophase(December)500hPa height field feature cannot be neglected to forecast drought and moist features of next summer in the east of Northwest China.