Combined with a high earth-rock cofferdam project on the thick overburden layer, this paper analyzed the stress sensitivity of Foundation Concrete diaphragm wall on the thickness of the diaphragm wall and main parameters of E-B model(k,Rf,Kb,Kur) by nonlinear finite element method. The results show that the stress and deformation distribution of the weir body, foundation and diaphragm wall are similar under various indexes, but with the increase of the diaphragm wall thickness, the principal tensile stress of diaphragm wall is significantly reduced and the principal compressive stress variations is relatively small. The main parameters of the E-B model have a significant effect on the stress of diaphragm wall. Compared with the case of adopting the basic parameters, using the larger model parameters will increase the principal tensile stress of the diaphragm wall, and the smaller model parameters will make the principal tensile stress of the impervious wall decrease. In engineering design, the appropriate thickness of cutoff wall and mix design of cutoff wall concrete should be chosen so that the main parameters (k,Rf,Kb,Kur) of the cut-off wall E-B model are relatively small.