The frequent occurrence of urban eco-environmental damage has caused damage to the urban atmosphere, water and soil environment, and has also caused ecosystem structural and functional degradation. It is extremely urgent to conduct research on urban eco-environmental damage identification and assessment technology. Because of the complexity and uniqueness of the urban ecosystem, it is difficult to determine the environmental damage in urban ecosystem and to carry out ecological restoration and damage compensation. It is urgent to establish a monitoring system to improve baseline credibility and reduce judgment deviation of the degree of damage, its scope, and the compensation for accountability. Based on related theories of urban geography and urban ecology, this paper analyzes the concepts, mechanisms, and characteristics of urban eco-environment damage, and then initially constructs a quadrat monitoring system to measure the undamaged state of different functional areas of urban ecosystems. To provide operational services for identification and assessment of urban eco-environmental damage and for carrying out special monitoring in damaged regions, we should adopt the strategy of using the existing eco-environment observation quadrat, while selecting and setting control areas.