In combination with the unique advantage of FLAC3D with explicit finite difference method in application to large-scale numerical analysis in geotechnical engineering area, and according to its shortage of pre-processing capability of building up complex numerical model especially for structural element model, a preprocessing software for FLAC3D based on HyperMesh is developed to solve this issue. The basic approach and flow diagram of the pre-processing program are expounded, and the node conversion rule of solid element and structural element between HyperMesh and FLAC3D is presented. Two typical excavation case histories, one with inside struts and retaining wall, another with soil nails and shot concrete covering, are given to demonstrate the engineering feasibility of the developed program.