Abstract: Ecosystem security is associated with sustainable development, the function of ecosystem security lies in supplying ecological service for human being. An attempt is made to assess the sustainability of ecosystem in various aspects of environmental degradation during the next few decades. Ecological appropriation as a tool for ecosystem security and sustainability assessment is widely used. The ecological appropriation presents a sample framework for national or regional natural capital accounting. In this paper, security and carrying capacity of ecosystem in Xichang, Sichuan, China was analyzed based on the theory of Ecological Appropriation. Analysis illustrates that the carrying capacity of ecological footprint is only 0.8 hm\+2, ecological deficit is per capita 0.6 hm\+2, the security of ecosystem is threatened due to resource exploitation dependence on local resource absolutely in Xichan; sensitivity analysis shows that the ecological footprint per capita will decrease 2.21%, ecological deficit per capita decrease 5.32%, while energy consumption decrease 10%; biocarrying capacity per capita will increase 9.92%, ecological deficit per capita will decrease \{14.01%,\} while agricultural output increase 10%. In this context, the goal of enhancing ecosystem health and stability through ecoindustry development forms effective and important measure. Development of ecoindustry is an essential tool for decreasing ecological deficit from the local level to regional level.

Key words: ecological surplus and deficit, ecological appropriation, ecosystem security, sensitivity analysis