The subways or underground construction have been built nationwide in 25 cities. The pre-assessment and systematic planning are requested for building a new metro lines. The reason is the inevitability that new construction projects have to face the various difficulties and geological environment risks in accordance with their diverse urban geological environment under underground space development and construction. Taking the Kunming City planning as an example, the sudy assesses the suitability and analyzes its high risk factors on urban underground space development and utilization, using the extenics research methods under complex geological conditions. It would provide a reference to underground space development in the similar urban geological conditions.