A multiscale and multi-physical model which could couple dislocation dynamics and finite element method was developed to simulate the mechanical response of nanostructural metals. The multiscale model can capture detailed dynamics evolution of dislocation structures and can predict macroscopic constitutive response. In addition, the developed model could account for complex multi-physical phenomena, which would play an important role in obtaining a fundamental understanding of deformation mechanism in nanostructural metals. To get a mechanistic understanding of plastic deformation mechanisms and corresponding macroscopic response of crystalline metals at micron- and sub-micron length scale, the multiscale modeling has developed to investigate size-dependent plasticity by coupling conventional continuum crystal plasticity finite element (CPFEM) with a discrete defect (DD) modeling. While the detailed defect microstructure and short-range interaction is handled by DD framework, the long-range elastic interactions with image stress field are calculated by CPFEM (using commercial package (ABAQUS) with user-subroutines), accounting for complex boundary conditions. The proposed 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. Applications of developed concurrent coupled model includes Taylor impact test, nanoindentation, and hydrogen embrittlement at submicron length scale. The developed model will shed light on fundamental investigation of “defect-controlled” mechanical behaviors in nanostructural metals.