Abstract: A three-dimensional numerical simulation is carried out to investigate the mechanical behavior of diaphragm wall during slurry trenching and concreting. The geotechnical program FLAC3D is employed to establish the numerical model and to study the influence of the construction on lateral displacement of trench face as well as ground surface settlement, which includes trench face reclamation, installation of concrete guide wall and the rigid concrete pavement as well as the adjacent completed panels. The numerical results show that there exists prominent stress redistribution around the individual panel, both horizontally and vertically. Slurry trenching leads to unloading effect owing to the lower bentonite slurry pressure compared with the in-situ at-rest lateral soil pressure, while concreting compensates the effect by exerting the greater liquid concrete pressure on the trench face. Horizontal arching effect can be neglected in Shanghai soft soil deposits when the panel width is over 5 m. The deformation restriction exerted by trench face reclamation on the superficial soil is more pronounced than that on the deep-level strata. The concrete guide wall and the rigid concrete pavement can only restrict the movement of superficial soil around the top of the trench. The adjacent completed panels give unnoticeable impact on the maximum displacement of soil around the constructing panel, owing to the weak horizontal arching effect.