The development of underground transportation based on TOD mode drives the process of underground development of surrounding commercial space, and the connectivity between underground transportation and commercial space has become a link that cannot be ignored. Based on the place theory, this study highly summarizes the spatial composition of the two connected Spaces of Shanghai People’s Square Station and Xujiahui Station. Considering the spatial structure and place spirit, field investigation and questionnaire distribution are conducted. Moreover, exploratory factor analysis and SPSS algorithm software are used to find out the strongly related reasons affecting the connectivity quality. By quantifying the subjective factors of pedestrians, five influencing factors are summarized, namely, central place and direction, regional division and shaping, spatial theme culture, spatial interaction, public safety and management, and corresponding optimization method are proposed to provide some reference for the design of underground connected space.