The paper analyzed the spatiotemporal characteristics of runoff in the middle and lower reaches of Weihe River basin,which could provide the basis for the depth research and rational development and utilization of water resources.It used the measuring data of typical hydrological station in the middle and lower reaches of Weihe river basin and analyzed the trend of annual runoff by using linear trend analysis, and investigated the spatial patterns of runoff by using the set pair analysis. The results showed that the runoff of Weihe River basin has presented the trend of decrease since 1970s, and the variation of annual runoff each hydrology station is similar;the variations of annual runoff in the middle and lower reaches of Weihe River has characteristics of synchronicity.The hydrological analysis method which based on set pair theory is simple and convenient, and the result is reasonable, which has promotional and application value in the study of change characteristics of runoff among the field of hydrology and water resources.