Abstract: Based on China's monthly precipitation data from 1950 to 2000 and by using Z-index, 4 categories of floods were estimated. Variation and change of floods in South China were analyzed in terms of percentage areas of floods. This study reveals that flood area in South China has a slightly decreasing trend in the latest 50 years. During the winter half year, however, it displayed an increase trend, especially since 1990. It is also found that flood area has deceased during the summer half year from April to September, but increased during summer, especially since 1990. In the early raining period, flood area has a decreasing trend, but it has a strongly increasing trend in the late raining period. The gradual wet trend during the winter the half year results in wetter climate condition for South China,which will be more favorable for spreading some of the epidemic pathogenic bacterium, crop diseases and insect pests.