[Objective] Based on the ERA5 reanalysis of precipitation data from 1950 to 2022, the spatiotemporal variation characteristics of precipitation in the water source area and water receiving area of the south-to-north water transfer project were explored in order to ensure the feasibility and sustainability of inter-basin water transfer, and provide a scientific reference for water resource scheduling and operation management of the middle route project of south-to-north water diversion project.[Methods] The Mann-Kendall test, wavelet analysis, cloud model, and Copula function were used to analyze the trend of precipitation change and the characteristics of drought-waterlogging encounters in the water source area and the water receiving area.[Results] ① During 1950-2022, annual precipitation in the water source area and the water receiving area of the south-to-north water diversion project has decreased by 34.75 mm/(10 yr) and 39.35 mm/(10 yr), respectively. The annual precipitation in the water source area and the water receiving area exhibited a main cycle of 43 years and 55 years, respectively; ② Precipitation in the subordinate cloud map was unevenly distributed and discretely dispersed in summer, while precipitation distribution was uniform and concentrated in winter; ③ The unfavorable water diversion encounter frequencies for the flood season and the non-flood season were 23.15 % and 25.92 %, respectively.[Conclusion] Annual precipitation in both the water source area and the water receiving area showed a decreasing trend. The alternating change of precipitation between the wet season and the dry season in the source area was significant. The probability of asynchronous drought-waterlogging was greater than that of synchronization, and the frequency of simultaneous drought in the north and the south was relatively low, which increased the safety and reliability of water diversion projects. These research results provide a theoretical basis for the formulation of relevant policies and technical guidance for the middle route project of the south-to-north water diversion project, and will be helpful in project planning and management, thereby improving the efficiency and sustainability of water resource utilization.