The excavation area of Hangzhou Xiaoshan Huarun Vientiane Project is very large and deep, and its location is very complex. The foundation pit is close to subway station and shield tunnel, river, large underground pipeline and buildings, etc. So it has a very high demand to control the deformation and leakage of foundation pit. How to successfully complete the construction of such projects worthy of extensive consideration and research. Based on the engineering construction examples, this paper summarizes and validates the applicability and reliability of the methods and technical measures adopted in the construction of the deep foundation pit under the complex environmental conditions and the analysis of the monitoring data, ensure the safety of foundation pit construction.