Danjiangkou reservoir is the water resource area of the mid-line project of south to north water division. Zooplanktons are monitored at thirteen ecological stations in Danjiangkou reservoir and its typical branch rivers in August 2010 in order to establish the scientific foundation of the databank of the long-term ecological research and the layout of ecological project of the water resource. The water samples are collected using standard methods. Saprobic system is used to evaluate the trophic status of the water resource area of the min-line project. The samples contained 154 species (varieties), 110 genera of zooplankton, of which rotifea is the most, accounting for 35%, followed by copepods, protozoa and cladoceran. There are 6 species (varieties) saprobic indicators, of which β-mesosaporbic indicators account for 66.7%. No hyper-mesotrophic indicators of zooplankton occurred in the water samples. Therefore, Danjiangkou reservoir is under β-mesosaporbic status and suitable for the requirement of the water quality of the mid-line project.