Computer programs have been developed to predict phase separation, flow-induced phase structure, and structure-dependent mechanical properties of binary polymer mixtures. The phase separation is simulated by solving a two-dimensional Langevin equation with Flory-Huggins free energy using the finite difference method under periodic boundary conditions. The change of phase structure due to flow is predicted by adding a shear flow term to the equation. By generating a finite element mesh from the calculated phase structure, the stress analysis is carried out for estimating the mechanical properties of the system using the finite element method. The elastic modulus and thermal expansion coefficient based on the phase structure were numerically investigated for various volume fractions and properties of components using the developed programs.