The phase field simulation of interface movement and interdiffusion microstructure in a binary diffusion couples was developed. The diffusion couples with nonequilibrium concentration for single phase or single phase and two-phase including the temperature and mobility effects were studied. It’s shown that the interface movement and the atoms diffusion direction were determined by the magnitude of relative concentration difference between the initial concentration and the equilibrium concentration, the distance of interface movement and interdiffusion flux increases as the temperature or the mobility increasing, and the large mobility makes the particles coarsening faster.