Discrete element method (DEM) is a powerful tool for the study of granular materials. Some issues in numerical modeling of DEM including parameter selection and mass/density scaling method are discussed. A new method to simulate the resin membrane in the laboratory which is more accurate and simpler is proposed. Using DEM, microscale behavior of soil including particle rotation and mesoscale void ratio distribution are analyzed. Failure modes and stain localization are revealed from the particle scale analysis. Configurations of the shear band are investigated. It shows that microstructure and micromechanics is the underlying mechanics of the macroscale behavior of the granular soil. Being a simpler, faster, and cheaper method compared with traditional experimental method, DEM can capture the discrete characteristics and provide deeper insight of the granular materials.