China is one of the countries facing the most serious water shortage crisis.In recent years,the water problem has become more and more projecting,especially for urban area where water shortage has been a common problem-water demand is mounting up rapidly due to population burgeon and improvement of living people's standards.The serious dearth of water has turned out to be a bottleneck in the region's social and economic development,which makes the research on water resource more pressing.In this paper,we mainly study the water resources carrying capacity(WRCC),as the groundwork of the study of water resources security stratagem,which plays an important role in the harmonious development of regional water-ecology-socio-economy complex system.Jingjinji region located in the Haihe River valley is chosen as a typical area to study the water shortage problem.This region includes Beijing,Tianjin and eight cities in Heibei province:Shijiazhuang,Tangshan,Qinhuangdao,Baoding,Zhangjiakou,Chengde,Cangzhou and Langfang,which is around Greater Beijing Economic Hub and is the core area of the Bohai Bay Trade Hub.Mean while it is severely short of water resources,the average water resources of which is only 370×108m3,1.3% less than the national average level,but it carries about 10% of the national population,food and GDP. A model of water resources is developed for analyzing the carrying capacity of water resources in different years in this region.The model for calculating WRCC is established by taking the "population capacity capacity" as its synthetic index and using the system optimizati-on method.And a formula of load factors is also used to compute the potential of water resources in different areas. The final results indicate that:1)There are still 684×108m3 of potential water resources which come from rain and flood in the region,and could be exploited.2)In the years of normal precipitation(p=50%),according to the "having enough to eat and wear" life standard,the population that water resources can carry is larger than that of nowadays;while,if according to the "better-off"life standard,the water resources cannot support today's population.3)In drought years,in developed area,the population can be carried by lowering the living standard,however,in underdeveloped areas,when having a long-term drought,the population cannot be supported.4)Although the water carrying capacity of Jingjinji region may be improved after completing the South to North Water Transfer Project,the living standard might not be improved,for it can be offset by the increasing population.So,the rudimentary method for solving the problem of water scarcity is stringent population control.