Nanostructured metals have attracted attention due to their appealing mechanical properties of good ductility and high strength. To understand the underlying mechanisms that control the mechanical properties of nanostructured metals, an insight into the role of the grain boundary in dislocation-driven plastic deformation is vital. In previous studies, the grain boundary has been observed as a dislocation source, sink or having no effect, which in turn, gives rise to different mechanical responses upon various loading conditions. With this motivation, our study characterizes dislocation interactions (absorption, transmission and nucleation) with the grain boundary via atomistic modeling, based on which we also developed a discrete dislocation dynamics model. With the atomistically informed dislocation dynamics model, we explore the effect of varying misorientation angle for pure twist and pure tilt grain boundaries on plastic deformation of nanostructures, which could provide a better understanding of dislocation driven plasticity for polycrystalline metals at small scale.