In order to analyze the change trend of precipitation in catchment of Miyun Reservoir,based on the long-term precipitation data obtained at 38 stations from 1956 to 2005,the Mann-Kendall method is used to study the change trend of extreme precipitation in one-day and three-days and the precipitation in flood period from July to August and annual average precipitation.In addition,the spatial distribution of precipitation is analyzed as well.The results shows that the precipitation in flood period has an obvi...