Storms are not only the improtant supply for water resources but also the important cause of for-mation of flood in Beijing City. This paper gives a storm designning formula for 13 time-intervals,T=5,10,15,20,30,45,60,90,120,180,360,720and 1440min. ,and 7 different recurrence-intervals,N=200,100,50,20,10, 5and2,at the Beijing Rainfall Station. Based on the time-intervals of 10 minutes,1 hour and 2 hours, this paper makes an analysis of the rainfall pat- tern on 120 minutes,12hours and 24 hours. The formula and the rainfall pattern presented in this paper can be effectiveiy used in the design of surface,lake and river conservancy engineering and the design of underground drainage pipeline.