Abstract: The characteristics of rainfall, water flow and salt tide in the Pearl River basin in 2021 were summarized, and the statistical analysis on the interdecadal background of less rainfall and weather climate system were analyzed, and the causes of drought in 2021 were preliminarily discussed. At the same time, according to the shortcomings and weaknesses in the prediction and early- warning of the drought relief and water supply in 2021, some thoughts and suggestions on the data resource integration, hydrological monitoring in dry season, the intelligent runoff prediction, and the hydrological drought indicators and so on were put forward.