Abstract: The deep excavation engineering of Outer Ring Tunnel Project in Puxi,Shanghai,is an open type one in plane with depth of 30 m and width of 43 m.This paper deals with the field study of deformation behind retaining wall,on top of wall and inside the wall.A synthetic method,including the systematic field monitoring,the application of SUPER Star software of space non linear design theory for deep excavation engineering and several prediction methods,is used to obtain the data of deformation in advance of two weeks for guiding construction at each stage.Engineering practice in this project has shown that the adoption of IT construction is successful and the rich data accumulated is valuable.The earth pressure is also studied to monitor the variation of behavior.A practical scheme for computation of active earth pressure is suggested.Finally,some important theoretic understandings for IT construction are proposed in this paper.