In recent years,with the rapid development of cities and the improvement of drainage design requirements,it is particularly important to study the characteristics and patterns of urban rainstorm.Based on the minute-by-minute rainfall data of Beijing Observatory station during 1961—2017,according to the Technical Guidelines for Establishment of Intensity-Duration-Frequency Curve and Design Rainstorm Profile,this paper established the rainstorm intensity formulas in Beijing under the two climate states of 1961—1990 and 1991—2017,and the design rainstorm patterns of 30 min,60 min,90 min,120 min,150 min and 180 min durations with 5 min as the time period under the two-year return period.Results show that:(1) The P-Ⅲ pattern distribution curve has the best fitting effect on the rainfall of each duration under the two climate states in Beijing,and the rainstorm intensity formula has the highest precision.(2) Compared with the rainstorm intensity formulas of 1961—1990 and 1991—2017,on the whole,the rainstorm intensity value of the latter under each return period is lower,but with the increase of return period,the difference in rainfall intensity between them increases.(3) During 1961—1990 and 1991—2017,the location coefficients of short duration rainstorm peaks are 0.436 and 0.382,respectively.Under the two-year return period,the positions of rain peaks during 1961—1990 are earlier than those during1991—2017.The accumulated rainfall of each duration increases slowly in the initial stage,increases rapidly before and after the rain peak,and then slows down significantly.