Abstract: At present, the scientific and appropriate utilization, the transition from plane development to vertical layered development, the ecogeological environment safety of megacity, and the sustainable resource utilization of underground space are of great significance. Hence, the coordinated relationship between utilization of underground space resource and protection of the ecogeological environment in Beijing is discussed from the aspects of strengthening the ecological baseline constraint and promoting the highefficient utilization of underground space resource. And then the threedimensional ecological red line of underground space is determined, and the assessment is carried out on the potentiality of underground space resource by considering the ecological environment protection, construction stateofart of city underground space, geological conditions, historical building protection, land ownership and construction development. Finally, the arrangement relationships among different functional facility systems are explored, and different coupled development modes of underground space, i.e. underground space + public service, underground space + municipal complex, underground space + multifunctional tunnel, underground space + metro transit, underground space + transportation complex and underground space + infrastructure corridor, etc. are proposed for different development demands.

Key words: megacities, underground space, threedimensional ecological red line, integrated development of underground facility systems