Abstract: According to ecological security status and major ecological problems in Chaoyang District， Beijing， the study chose 15 characteristic special indicators to build the index system of ecological security evaluation based on the pressure-state-response （P-S-R） model. Based on the determination of the weight of index with the help of analytic hierarchy process， comprehensive evaluation is used to assess the ecological security situation in Chaoyang District from 2007 to 2010. The results showed that the aggregated index was 0.5315 and 0.5470， respectively in 2007 and 2008， which meant the eco-security level of Chaoyang District from 2007 to 2008 was in a poor state; the values for the period from 2009 to 2010 varied from 0.5547 to 05556， which meant the eco-security level was in an average state. In general， the eco-security index was low and the state of ecological security in Chaoyang District was poor， but the overall situation was getting better year by year. The ecological construction management and decision-making could be supported in light of the results obtained for a better ecological situation in Chaoyang District.

Key words: pressure-state-response model, analytic hierarchy process, the weight of index, ecological security