Abstract: The three-dimensional nonlinear numerical analysis of the ultimate pull-out resistance capacity of suction caissons in inhomogeneous soft clay was presented.The finite element software ABAQUS was utilized and numerical computations were conducted through the numerical analysis,and the effect of the contact state of the interface between the soil on the active side and the caisson upon the pull-out resistance of the caissons during its operation was studied.It was shown that the bonding or debonding conditions between the soil on the active side and the caissons were affected by the undrained shear strength of the soft subsoils,the aspect ratio of the caissons,the position of the attachment point and the inclination of the pull-out force.The rationality of the proposed numerical procedure based on FEM was validated by comparing the present solutions with experimental data and the results computed by the upper-bound limit analysis for a given model test.