Abstract: Deformation and stability due to the interaction between soil and retaining structures are the primary problems in geotechnical engineering.As a part of the continuous effort,the authors introduce an approach to simulate the soil-structure interaction numerically using the combined FLAC(Fast Lagrangian Analysis of Continua) and DEM,in which the soil is simplified as the collection of packing particles of rigid disks to be described by DEM while the retaining structure is viewed as one with the possibility of large strain and can be analyzed by the finite difference method.Smooth transition across the continuous/discontinuous domains is obtained by imposing the compatibility condition and equilibrium condition along the boundaries in the course of computation.Application of the proposed approach is discussed.A case study of a shoulder retaining wall acted by soil backfills is provided thereafter,showing the applicability of the proposed method.