This paper uses ground precipitation observation data from 12 national-level automatic weather stations in Qiannan Prefecture, Guizhou Province from 1989 to 2019, and uses methods such as climate tendency rate, linear regression, Kriging method, sliding t test, and weighted analysis of rainstorm risk factors to analyze Guizhou Province. The temporal and spatial distribution characteristics and risk areas of the torrential rains in Nanzhou from 1989 to 2019 mainly draw the following conclusions: (1) The number of rainstorm days in Qiannan Prefecture is showing an increasing trend. The rainstorm mainly occurs from May to September, and the heavy rainstorm mainly occurs from May to August. (2) The heavy rain in Qiannan Prefecture has two major centers, which are located in the Duyun area in the middle east and the Changshun area in the west; the heavy rain in Qiannan Prefecture is mainly in the Duyun to Sandu area, and secondly affects the Changshun area. (3) Heavy rains in most areas of Qiannan Prefecture show an increasing trend. There are mainly three strong centers in the climatic tendency rate of heavy rains, namely Changshun, Guiding, and Sandu. (4) June torrential rains are concentrated in Duyun area. From July to August, there is more in the south and less in the north. September is more in the east and west and less in the middle. Heavy rains are more in the east and west in May and less in the north and southeast, and concentrated in the east in June. In the Yun and Sandu regions, August was mainly concentrated in Sandu in the east and Changshun in the west. (5) There was a sudden change in the number of rainstorm days around 2013. The historical risk area and trend risk area of rainstorm are mainly in the East and West, and the proportion of the sum of high-risk and high-risk areas is 30.3% and 28.1% of the total area of Qiannan Prefecture, respectively.