The evaluation index of ecological security system was built using the PSR(pressure—state—response) model,entropy method was applied to define the weights of seventeen assessment indexes,and the Excel software for data processing was used to evaluate the ecological security of Shengzhong Reservoir. Results showed that the ecological security situation from 2004 to 2007 was improved. At last,several environmental protection measures for reservoir ecosystem were discussed,such as banning cage farming fertilizer,strengthening the solid waste and wastewater treatments of reservoir residents,controlling soil erosion,reducing point source and non-point source pollution by nitrogen and phosphorus,preventing the spread of water hyacinth,focusing on the management of water eutrophication,and maintaining the reservoir storage capacity in a reasonable level. At the same time,it should be noted that the new factors such as reservoir fishing or other factors affected the ecological balance of Shengzhong Reservoir.