In recent years there has been a great deal of research on the subject of nanostructured materials. Structure across a range of length scales has been of particular interest. Theoretical modeling of nanostructured formation in polymer blends has gained considerable momentum due to the increased interest in nanostructures, such as nanoparticles, nanotubes, nanopores, and so on. Polymers show universal behavior on long length and time scales. Usually, the size of an ideal polymer is calculated from the freely jointed polymer chain model. The solubility and interaction parameters in nanostructured polymer blends are reviewed. Several computer simulation models for predicting mechanical, electrical, and thermal properties of semicrystalline polymer and nanostructured polymer blends are discussed. Modeling of polymer in solution and the morphological control of nanostructured blends are also reviewed. Further development of nanostructured polymer blends depends on the fundamental understanding of their hierarchical structure and behavior, which requires multiscale modeling and simulation to provide various lengths and time scales. Atomistic-based simulation such as molecular dynamics, Monte Carlo, and molecular mechanics are addressed for the multiscale modeling of nanostructured polymer blends for material design. A mathematical model based on the Cahn–Hilliard nonlinear theory of phase separation is also discussed.