Modern buildings are large in volume and have deep foundations,which can easily lead to the leakage and recharge of surface water. When the impermeable soil layer serves as the foundation bearing stratum, it is extremely likely to cause the \water - basin effect\ resulting in the floating of the building and thus damaging the building structure. Therefore, it is very necessary to study and analyze the dewatering and drainage scheme and construction technology for the deep foundation pit on the impermeable soil layer. This paper analyzes the on - site construction of the pressure limiting well project of the LongTan TOD project and proposes relevant optimization measures to improve the construction quality of the pressure - limiting well project.