Abstract: This article presents a large number of extreme values of the point rainfalls around the world and derive a new envelope curve formula for enveloping the world's greatest known point rainfalls,R=491D^0.452 (R is the rain,D is the duration of rainfal).In the end,it gives a brief explanat ion to characterize the regional distribution of the world's greatest point rainfalls, the causes of storms and the use of extreme values point storms in the probable maximum precipitation estimation.