Annealing was carried out to produce Ag-Cu dual-nanophase composite by decomposing Ag-Cu supersaturated solid solution prepared by ball-milling. Differential scanning calorimetry, X-ray diffraction, and transmission electron microscopy were used to characterize the growth kinetics of the nanophase composite upon heating. The results show that bimodal growth kinetics is obeyed in the dual-nanophase system. The coarsening of the second phase of small volume fraction follows the cubic law of LSW theory, while the grain growth of matrix phase follows the kinetic equation of the grain growth of pure nanocrystalline metals. In both cases, the growth is controlled by grain boundary diffusion.