Nano-architectected metals can exploit the combination of resilient architecture with size-dependent enhanced properties at nanoscale to achieve exceptional mechanical performance. Understanding fundamental deformation mechanisms in these noble materials requires capturing both microstructure evolution driven by defects and corresponding macroscopic mechanical response. With this motivation, we have recently developed a mesoscale defect dynamics model to concurrently couple dislocation dynamics (DD) modeling with finite element method (FEM). In this talk, mechanical behaviors of nanostructures such as nanolattices and nanoporous metals will be discussed, addressing the role of dislocation plasticity. Our model shows architected structures could exhibit increasing strength with decreasing unit cell size, which agrees with experimental observations. Closer examination at the dislocation microstructure shows plasticity is localized at the structures’ nodes due to high stress concentration. In addition, a new computational design guidelines for enhancing mechanical properties of metal alloy will be presented especially for nano-structural metals containing various defects such as nanoprecipitates, different phases, and nanovoids.