Abstract: Deep excavation in a city faces the strict environmental demands and unconventional excavated sections.And the files for the underground of the surroundings are often absent.A case study in Beijing is introduced.During excavation,the retaining structure was modified two times based on the original design and construction conditions.Three schemes of the retaining structure are calculated by plane finite element method.The monitoring records of horizontal deformation are compared with the results of FEM.It is emphasized that more attention should be paid to the files of the underground engineering.Meanwhile,the design of the retaining structure must be corresponded with the surroundings of the construction.