In the past forty years,some environmental factors closely related with evapotranspiration in North Henan Province have greatly changed.For example,evaporation from water surface decreased,relative humidity near to the ground surface increased,sunshine hours reduced and wind speed decreased.Similar to the problems of seasonal running dry of Yellow River and ever-lowering ground water table in the region,the change of these environmental factors might partly reflect the change of environmental quality ecologically.Our results showed that the change was mainly caused by humane activities,such as marked increase of irrigation areas and improvement of low-yield farmland in large area.Great attention should be paid to the problems resulted from the change of these environmental factors.