Water conservation in an ecosystem is one of the important service functions with which the ecosystem provides human being.Vegetation structure type,vegetation overlay degree,the earth surface cover condition,and soil physical and chemical properties were selected and quantified scientifically.Various digital maps were made separately by using ArcView software.By using AHP method and referring to the results from the expert system,a judgment matrix was constructed,various indicator weights were determined,and digital maps of various indicators were superimposed synthetically.The classification map of protected ecological function area for water conservation in Hebei Province was obtained.The protected ecological function area covers the water source areas of big cities in the province and the regions such as North Hebei Province,Mt.Yan,and Mt.Taihang.