In order to solve the issues of server pollution from tributary in upper section of Hanjiang River, low eco-environmental quality and some potential threat and to protect the water resources in Middle Line South-to-North Water Diversion, the aquatic ecology index system and weight and system dynamic model which could be used to evaluate the water ecology carrying capacity were developed based on the frame model of driving force-pressure-state-influence-response. Based on the combination of system dynamic model and membership degree, the water ecology carrying capacity of Shaanxi section, Hanjiang River were evaluated quantitatively. Moreover, seven regulation scenarios were implemented to investigate the response degree of water ecology carrying capacity in Hanjiang River (Shaanxi section) based on social development and technological level. The results show that Hanjiang River is now in the low load capacity on the current development and the water ecology carrying capacity will be improved largely and it will be up to the basic load capacity after the implementation of seventh regulation scenario.