Abstract: To solve the common problems associated with the underground space complex design under the city park, such as traffic and passenger organization, an indepth study is conducted based on the design experience of largescale underground space in and across China regarding traffic network establishment, passenger flow attraction, customer detainment, and fire evacuation in Taihu square in Wuxi, China, integrating rail transit, municipal highway tunnel, park, and commercial development as an example. The following results are obtained: (1) through efficient planning, connecting multiple modes of transportation with the surrounding underground spaces, a threedimensional transportation network on ground and underground can be built, improving the efficiency of urban operation and green travel; (2) targeted theme of Sunken squares can be designed for different passenger flows; (3) high headroom and clear spatial context could be adopted to create a comfortable space environment; (4) evacuation problems can be solved by connecting the Sunken squares with the refuge walkway; (5) through the appropriate use of various professional fire protection measures, fire protection in gray spaces can be realized ingeniously, reducing ground buildings and establishing a garden city.

Key words: Taihu square, Sunken square, fire evacuation, transitoriented development model, underground space complex, carbon neutral