Abstract: Focus is placed on the mechanical behavior and shear band formation in idealized cemented sands by a series of DEM biaxial compression tests involving different bond strengths and confining pressures. The DEM software PFC^2D is applied with user-defined contact model, which is resulted from the mechanical tests on the bonded granules idealized by two glued aluminum rods. The results show that the cemented sands have a higher strength and more significant post-peak softening and dilatancy than the reconstituted sands, and that the simulation is consistent with the laboratory tests and closely associated with the micro bonded contact mechanism. In addition, the shear bands in the cemented sands form with the simultaneous localization of micro parameters, such as deformed specimens, void ratio, averaged pure rotation rate (APR), displacement field and distribution of bond breakage.