Abstract: The foundation pit is about 190 m long,98~195 m wide, and presenting the shape of "L". The base burying depth is different(the depth of the main body is 10. 4 m,the depth of the sections is 6. 48 m). Existing sinks greenbelt in the middle part of the east(5. 88 m deep),the project is divided into phase 2 construction. The foundation pit will be protected by using "φ600 soldier pile wall + soil nailing wall above the pile".The foundation pit excavation are influenced by diving water and confined water, using "φ1200 mm rotary jet and mixing cement-soil pile" between the adjacent pile of foundation pit protection. That will be biting with the pile of foundation pit protection to form a curtain for cutting off drain, and the diving water will be drainaged to clean within the curtain, the confined water below the basement nearby will be drainaged to clean within the curtain. In order to ensure that groove bottom of the main body foundation pit,and the elevator well bottom, and the sump pit are not to be outburst flood during excavation.