The multiscale defect element method (DDEM) method has developed to couple 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 code, accounting for complex boundary conditions. In addition, the proposed model could account for complex multi-physical phenomena, which would play an important role to obtain a fundamental understanding of deformation mechanism at small scale. The unified concurrent coupled model will shed light on fundamental investigation of “defect-controlled” mechanical behaviors in crystalline materials, such as plasticity, damage and fracture.