Urban public space reflects a city's political, economic, cultural, style, taste and other conditions.It has not only ecological significance, but also social and cultural functions.A good urban design and public space is one of important means to create a civilized and harmonious city.Therefore, the pros and cons of urban public space design should be measured to achieve the complex ecosystem balance.Based on complex ecological concepts, from the realization of the theory of complex ecosystem balance, combined with China's national conditions, the comprehensive evaluation index system of city's public space design to be built, including social ecology, natural ecology and economic ecology this three objectives layers.The design objectives which the indicators of specific evaluation system should meet have been interpreted, and at the same time, the ways and means of their application were introduced, and the evaluation stresses the combination of quantitative and qualitative, which is in line with the authenticity of architecture and urban design and is workable.