College of Construction Engineering��Jilin University��Changchun 130026��China

There exists synchronous growth in resources consumption and environment pollution in Kunming urbanization in recent years��which has led to the increasing pressure of urban sustainable development�� Considering the environmental and social benefits in Kunming's water resources sustainable development��the authors provided a research finding the optimal urban population scale in different stages for urban water supply based on the sustainable development groundwater evaluating theoretical model�� Through the research on the availability of construction site as well as the risk in underground space exploitation with the extenics theory method��we get a suitable partition map of land for urban construction and a risky partition map of underground space development�� The results show that the appropriate population scale of Kunming will be less than 2. 96 × 106 by 2020��and will reach ( 4. 34--2. 96) × 106 optimized population scale after 2020 under the condition of economic- socially and environmentally sustainable development�� It is significant to optimize urban construction land and use underground space under the condition of land resources sustainability in Kunming��