The study about the temporal and spatial variation characteristics of rainfall and rainfall erosivity and theirs causes was significant to monitor, evaluate, forecast and govern local soil erosion. The Wei River basin, a typical arid and semi-arid area in China, was selected as a case study. The change trends of rainfall and rainfall erosivity were analyzed by Mann-Kendall test. The heuristic segmentation algorithm was employed to detect the mutation points of the rainfall and rainfall erosivity in the Wei River basin. The cross-wave analysis method was used to explore the relationship between ENSO (El Ni?o-Southern Oscillation), Arctic Oscillation, Sunspot and rainfall as well as rainfall erosivity. Results indicated that:(1) Rainfall and rainfall erosivity both showed downward trends; (2) There were change points in the rainfall series at Huashan and Xiji stations, and change points in the rainfall erosivity series at Huashan and Lintao stations, and these change points implied that the consistency of rainfall amound and intensity at some stations in the Weihe River Basin was destroyed; (3) All of ENSO, Arctic Oscillation and Sunspot variations showed strong impacts on the rainfall and rainfall erosivity variations, and the impacts followed the order of Sunspot > ENSO > Arctic Oscillation. The results would be helpful to guide the agricultural production, the construction of soil and water conservation and ecological restoration of the Weihe River basin.