The South-to-North Water Diversion Project (SNWDP) causes changes in the extreme climate of the area involved, and in turn the extreme climatic events will also impact the operation of the water diversion project. The study constructs an extreme meteorological element index system based on the meteorological observation data from 1960 to 2020. It quantifies the change degree of extreme meteorological elements in the area affected by the South-to-North Water Diversion Project using the range of variability approach (RVA) and the set-pair analysis (SPA) method, which reveals the evolution patterns of regional extreme meteorological elements under the impacts of economic development, climate change and the South-to-North Water Diversion Project. The results show that under the influence of economic development and climate change, the comprehensive change degree of extreme meteorological element indices in the South-to-North Water Diversion influence area from 1960 to 2020 exhibited an upward trend in a whole with obvious regional differences. The change degree of extreme climate in the central line area was significantly larger than that in the eastern line area, while the changes in water source area of the two lines were smaller compared with those in the transmission area and the receiving area. A comparative analysis before and after the water diversion shows that the impact of the project on the central line was greater than that on the eastern line, and the changes of extreme meteorological elements in the receiving area were more significant. Analysis of extreme meteorological elements reveals that extreme evaporation was significantly affected by climate change and economic development, extreme temperature was greatly affected by the impact of the water diversion project, whereas the extreme precipitation was not sensitive to the external perturbations.