The potential evapotranspiration were calculated based on the data of temperature,precipitation,relative humidity,sunshine duration,and wind speed from 12weather stations located in the upstream of the Weihe River and the data of runoff from the Beidao hydrometric station from 1971to 2008.The characteristics of regional climate change and runoff in the upstream were discussed and their relationship was studied using the methods of Mann-Kendall and climate inclination rate.Results showed that the mean temperature had increased by 0.3℃every ten years in the area since 1971and the catastrophic point was in 1994.Precipitation varied with periodicity and its catastrophic points were in 1994and 2004.The potential evapotranspiration had increased by 23mm every ten years in the area since 1971and catastrophe point was in 1993.This indicated that the monthly runoff varied with precipitation.The runoff had decreased by 2.57×10⁸ m³ in every ten years and catastrophic point was in 1991.The runoff had significant correlations with temperature,precipitation and potential evapotranspiration and the model for simulating runoff with precipitation and potential evapotranspiration was set up.Because of the raised temperature,potential evapotranspiration increased and precipitation decreased,which caused the expenditure of surface water increased and the income of surface water decreased in the upstream.The runoff in the upstream of the Weihe River decreased in recent years.The dropping of runoff in the upstream would bring about stress for water resource safety in the downstream of the Weihe River.