The invention relates to a method for calculating and processing inrushing destruction of an excavation and depressurization coupling effect of a foundation pit with confined water. The method comprises the following steps of: (1) selecting a calculation range for the depressurization seepage field and the excavation stress field model of the foundation pit; (2) defining the attribute of a soil material around the pit within the calculation range; (3) creating a geometric solid model by using a finite element program, and carrying out element discretization; (4) setting boundary conditions for the depressurization seepage field and the excavation stress field model of the foundation pit; (5) carrying out finite element analog calculation on the excavation and depressurization coupling effect of a foundation pit model; and (6) obtaining the inrushing plastic failure distribution diagram for the soil around the foundation pit with confined water according to the calculated result, and judging whether the foundation pit can inrush or not. Compared with the prior art, according to the invention, the action of the coupling of a foundation pit excavation effect and a depressurization seepage effect is considered, and the shear strength, the heterogeneity and the elastoplasticity of the soil around the pit are considered, thus the defects of the traditional foundation pit inrushing judgment method are made up, and the accuracy and the reliability for the judgment of the inrushing destruction of the foundation pit are enhanced.