This paper exploits the regional climate mode PRECIS (Providing Regional Climates for Impacts Studies) to analyze the changes of the drought and flood indices in South China in the middle and later period of the 21st century under the SRES A1B (Special Report on Emissions Scenarios A1B) scenario compared with the climatic reference period (1961-1990). Plenty of drought and flood indices are utilized first to verify the capacity of PRECIS for drought and flood indices simulation. Possible changes of the future drought and flood conditions in South China are preliminarily discussed. Results indicate that PRECIS can well simulate yearly and monthly changing features of the selected drought and flood indices. Under the SRES A1B scenario, the frequency and intensity of extreme precipitation event in South China in the middle and later period of the 21st century will increase dramatically, and the period of precipitation extreme will increase too, thereby the possibility of flood disaster occurrence will grow to a large extent. Meanwhile, possible changes of meteorological drought in spring, summer and autumn in South China is not obvious, but in winter the possibility will rise, especially in the winters of the last thirty years of the 21st century, the possibility will be higher.