Tsim Sha Tsui is one of the most important CBD areas in Hong Kong. From early 2000s, a new underground pedestrian network was being developed to extend the original Tsim Sha Tsui Metro Station to access a broader scope. This paper introduces statistical analyzes on land use, pedestrian flows, pedestrian trajectories as well as qualitative investigation on planning strategies, urban renewal and real estate development to answer the following research questions: How people use this underground space network as a second level of regional pedestrian system parallel to the surface street network? How this underground pedestrian system distributes people to improve accessibility of commercial land use? How newly-developed large-scale shopping mal...