Due to the consideration of anti-floating and shield launching safety, the foundation pit of an ultradeep circular shield launching shaft was dewatering outside the pit. However, the surrounding strata settlement was large. The dewatering was stopped and the original groundwater level was restored according to the requirements. In this paper, based on the field monitoring, theoretical and numerical methods were used to study the influence of anti-floating and permeability coefficient of the foundation pit on the retaining structure under high water level. The results show that the foundation pit can rely on the self-weight of retaining structure to resist the buoyancy of groundwater without considering the friction between retaining structure and stratum. Under the same water level, the permeability coefficient of the soil layer at the bottom of the retaining structure is the main factor affecting the uplift of the retaining structure.