In this paper, DDA (discontinuous deformation analysis) is used to study the mechanical characteristics of coarse granular materials. In order to establish the numerical simulation specimen, the 2-D random particle generating algorithm of granular materials is studied. Loose particles are randomly generated according to the gradation curve. Under the action of the gravitational load, the packing process of the particles inside a rectangular container is simulated by DDA so that a heap of the particles which contact each other is formed. On the basis of the heap, the specimen is then established. With reference to the loading process of the tri-axial laboratory test, 2 D numerical simulation on the mechanical characteristics of coarse granular materials is performed also by the DDA. The stress strain curves obtained by the numerical simulations are basically in agreement with the results by the tri axial laboratory test. It indicates the numerical simulation is suitable for the mechanical characteristic research of coarse granular materials. In addition, the distribution of several fabric elements about interaction between particles is also prese