Abstract: Using natural river runoff data from Xijiang Gaoyao, Beijiang Shijiao, and Dongjiang Boluo Stations in the Pearl River Basin from 1956 to 2016, the characteristics of runoff changes and development and utilization of each river were analyzed; Based on the percentage of percentage deviation, the changes in wet and dry seasons were evaluated; And based on the combination of empirical probabilities analysis, the probability of encountering low water and the probability of continuous low water for three major water systems were analyzed. The results show that:①Xijiang River has abundant runoff with a small interannual variation; The runoff of Dongjiang River is relatively small, with significant interannual variations. ②The runoff of the Xijiang, Beijiang and Dongjiang rivers varies greatly throughout the year, and drought is prone to occur during the dry season.③The probability of encountering Xijiang and Dongjiang in dry years is much lower than that of encountering Beijiang and Dongjiang in dry years. ④ The probability of three major water systems experiencing a dry year at the same time is 14.7%, and the probability of experiencing a extremely dry year at the same time is 6.6%.⑤In the past 61 years, there have been consecutive dry seasons for more than two years, with 3, 6 and 4 occurrences in the Xijiang, Beijiang, and Dongjiang rivers respectively. These results have a guiding role in optimizing the allocation of water resources in Guangdong Province, storing peaks and supplementing lacks in time, and using abundant resources to replenish dry in space for supporting high-quality socio-economic development.