Abstract: City is an artificial and natural composite system. Economy，environment and society systems of a city have a relation of mutual influence and resonance. Ecosystem of a resource-based city is more vulnerable than that of an ordinary city and has obvious complexity，fragility，ecological sensitivity and heterogeneity. With Erdos City，Inner Mongolia，China as an example in ecological fragile region，the paper used a principal component analysis evaluation model，and SAS software to assess the city ecological environment impact in the period of 2003-2011. Understanding the ecological situation in Erdos City，and the establishment of safety regulation of city ecological environment management system. The results showed that the overall Erdos City ecological system is in an unstable state of development. The development level of ecological quality sub-system has been rising steadily and has a gradually improving trend. The maximum value is 1.273 6 in 2011. The minimum is -0.821 6 in 2003. The difference is 2.095 2 between the maximum and minimum. The development level of environmental quality sub-system presents a tendency of declining firstly，and then increasing，and last decreasing. The minimum is 0.247 3 in 2006. The maximum value is 1.172 5 in 2003. The difference is 0.925 2 between the maximum and minimum. The level of development of environmental management sub-system is steadily increasing with slightly fluctuation. The maximum value is 1.512 in 2010. The minimum value is 0.173 in 2003. The difference is 1.339 between the maximum and minimum. In general，the total development level of Erdos City ecological environment influence is in a rising and with slight fluctuation state. The main reason is that the per capita public green area of the city，built-up area green rate，per capita road area and so on have been significantly improved during this period，although the city population increased significantly. Based on the status of city ecological environmental impact，the regulation and control strategy of Erdos City include：formulating city ecological planning including city ecological function zoning，protection planning of fragile city ecosystems，ecological capacity determination，the natural ecological protection and construction，green space planning，city land use planning，resource utilization and conservation planning and so on; and legitimately developing and utilizing of coal resources with emphasis on ecological environment and restoration mines. Thereby the measures including curbing the land，pasture，arable land reduction and destruction; strengthening cleaner production in coal industry and developing clean coal technology; increasing investment in the construction of environmental protection; strengthening inspection，coordination，supervision and guidance of environmental protection in the production process; developing the environmental concept and awareness of city residents and motivating their environmental enthusiasm and participation and uplifting environmental supervision and management should be adopted in Erdos City，on one hand to improve city environmental infrastructure construction investment，and on the other hand to increase environmental pollution control and environmental management capacity building investments.

Key words: resource-based city, ecological environment, impact assessment, regulation, Erdos City