Dongjiang River plays a critical role in the water supply safety system of the Guangdong-Hong Kong-Macao Greater Bay Area. It is of great significance to explore the rainfall changes and future trends for the efficient development and utilization of water resources in the Dongjiang River Source Area. Based on the rainfall data of 24 representative meteorological stations from 1956 to 2022, the characteristics of rainfall changes on the intra-annual and inter-annual scales were studied by means of Mann-Kendall mutation test and wavelet analysis. Subsequently, the future rainfall trend changes were predicted by Hurst coefficient and correlation function method. The results show that the ratio of rainfall in dry season to flood season was about 3∶7, the concentration degree was 0.12-0.60, and rainfall mainly concentrated in May. The intra-annual distribution of rainfall showed a trend of discretization in the study period. The rainfall concentration period of Xunwu River was advanced by 4 days, and Dingnan River by 11 days. In terms of inter-annual changes, the rates of annual rainfall of Xunwu River and Dingnan River only increased by 0.74 mm and 0.86 mm per year, respectively, with a principle cycle of 16 a. It is predicted that the study area will still be in the period of low rainfall in the next few years. The Hurst coefficient of rainfall is greater than 0.5, and the correlation function value is close to 0, indicating persistent rainfalls with little variations. It is found that the rainfall concentration period is advanced, the annual distribution trend is flat, and the recent annual rainfall is in a low period. It is suggested to strengthen the prevention of mountain flood disasters induced by strong rainfall events before flood season, and make full use of the water resources in small and medium-sized reservoirs after flood season. Hence, the safety of agricultural and domestic water use in autumn and winter can be improved, which is an efficient approach to adapting to the changing environment of rainfall in the Dongjiang River Source Area under climate change.