Based on the results simulated by PRECIS (Providing Regional Climates for Impacts Studies), which is developed by the Hadley Centre for Climate Prediction and Research, the changes of floodseason heavy rainfall under tthe SRES B2 scenario over South China during 2071〖CD*2〗2100 are analyzed. It is shown that PRECIS has the capability to simulate floodseason severe heavy rainfall. The percentage of severe heavy rainfall to total rainfall in 2071〖CD*2〗2100 would increase relative to 1961〖CD*2〗1990 (the baseline). The percentage of the number of severe rainnig days in 2071〖CD*2〗2100 is analyzed, and the results show that there would be a maximum center in the centralnorth part of Guangxi and the northern Fujian during the earlier floodseason, and there would be a maximum center in Guangdong and Fujian during the later floodseason. The change percentage in each month during flood season is positive over South China except for Hainan. The occurrence frequency of floodseason severe precipitation events in 2071〖CD*2〗2100 would increase obviously.