Taking the foundation pit construction of the comprehensive station area sheared by a Nantong subway station and Nantongxi Station of Shanghai-Nantong railway as an example, this paper introduces the real time monitoring of the whole process of the foundation pit enclosure and the excavation in the construction of the deep foundation pit of a reserved Nantong rail transit station. Based on the analysis on the monitoring data, the enclosure and monitoring schemes are further demonstrated to ensure the safety of subway foundation excavation and railway viaduct construction in the same period.