The triaxial compression test is the most common laboratory test used to measure the shearing mechanical properties of granular soils. In this paper, a series of numerical drained triaxial compression tests were performed in laboratory with different confining pressures on calibrated glass-beads ranging from 1.25 mm to 2.0 mm in diameter. The confining pressures used for the triaxial tests were 50, 100, and 200 kPa. A model was developed using the Discrete Element Method (DEM) and computed by Particle Flow Code in three dimensions (PFC3D) for the simulation of the triaxial compression tests. The model specimen was an assembly of spherical particles, which were defined by a set of micro parameters, idealized using a stiffness contact model. The influence of several micro parameters as the friction coefficient, normal stiffness and shear stiffness on the stress-strain behavior of the beads was analyzed. Numerical test results show that the micro parameters of the model can greatly influence the macroscopic behavior of the glass-beads. The calibration process was validated by comparing to the experiment results. The relationships between micro parameters and macro parameters were built for further glass-beads analysis. It was showed also that the DEM can accurately capture the very small-strain behavior of the glass-beads and to predict the elastic modulus, Poisson's ratio, angle of friction and dilatation angle. (C) 2020 Elsevier B.V. All rights reserved.