The invention relates to a method for calculating and predicating post-construction settlement of a suspension seawall. According to the method for calculating and predicating the post-construction settlement of the suspension seawall, the accuracy for calculating and analyzing data is improved. According to the technical scheme, the method comprises the steps of a, determining the variable quantity between soil geological parameters before and after the blast action, dividing the soil disturbance range into a plurality of disturbance areas, and determining the strength reduction coefficient f of soil of the different disturbed areas by the blast; b, setting up a whole calculating model of the seawall foundation by a finite difference software FLAC, and dividing finite element meshes according to the soil disturbance range; c, selecting an elastic-plastic constitutive model suitable for saturated soft soil; d, initializing crustal stress calculation, and verifying the reasonability and accuracy of the elastic-plastic constitutive model; e, further conducting numerical calculation, obtaining the relations between the post-construction settlement and time, between the post-construction settlement and loads and the like, analyzing and predicating the post-construction settlement, and summarizing the change law of the post-construction settlement of the foundation soil under the different working conditions.