An ecological security assessment index system of Zhongshan city was constructed based on the Pressure-status-response conceptual model. The weight of each index was determined by the Analytic Hierarchy method, and the values of ecological security assessment index were calculated. The results showed that the safety values of ecological environment pressure, ecological environment status and humanity response subsystem are 0.1601, 0.2677 and 0.2736, respectively. The comprehensive value of ecological security is 0.7014. The level of ecological security of Zhongshan city is relatively safe. It is concluded that, under the control of humanistic response subsystem, the status of ecological environment is good. The pressure of ecological environment is relatively small. The status of population-resource-environment-economic compound system is relatively harmonious. But the comprehensive value of Zhongshan city is close to critical safety value. It is necessary to optimize ecological environment and improve landscape ecological pattern.