Based on the daily precipitation data of 29 meteorological stations in Sanxia reservoir region from 1961 to 1994,a climatic analysis of the dates on which the first heavy rain occurred in the region after the dry seasons is carried out. The region is divided into the east and the west parts, and the dates of the first heavy rain in the two parts are compared. The statistical results obtained provide a valuable reference for the current construction in Sanxia region.