Cementitious material can be considered consisting of particulate elements on the levels of the microstructure and mesostructure. HADES is a concurrent algorithm-based program, designed to simulate the mixing or flow of granular material encompassed arbitrary particle shapes. In this paper, a specific technology is employed to generate the single aggregate particle of arbitrary shape in HADES. Then with the HADES toolbox materials structure can be formed. Based on these work, concrete is taken as an example of a typical cementitious material. With the simulated meso-structure of concrete from HADES, interfacial transition zone (ITZ) is enriched and a special tool is employed for the meshing of aggregates, cement paste and ITZ. After that finite element method is used for the analysis of stress and strain within the meso-structure. The calculation results show that the approach to simulate cementitious material, of HADES packing, then meshing and finally finite elements analysis, is feasible and effective and the numerical prediction of elastic modulus of concrete consisting of three-phase material is in agreement with effective.