The multiscale defect element method (DDEM) method has developed to couple conventional continuum crystal plasticity finite element (CPFEM) with a discrete defect (DD) modeling. The multiscale model could account for complex multi-physical phenomena, which would play an important role in obtaining a fundamental understanding of deformation mechanism at small scale. Using the model, we investigate the mechanical behavior of nano-architected materials. The mechanical response of nanoscale octet-truss lattice structures under compression obtained from this model is compared with experimental results and a scaling model for the strength of the nanolattice structures is developed. The multiscale model will expand our knowledge on governing mechanism of plasticity controlled by defects in crystalline materials.