A　hybrid　thermodynamic/Cellular　Automaton　(CA)　model　was　developed　by　introducing　the　thermodynamic　functions　of　the　nanocrystalline　metals　into　the　CA　simulation　algorithm　The　Gibbs　free　energy　of　the　nanocrystalline　material　is　the　sum　of　the　energies　of　the　nanograin　boundaries　and　the　nanograin　interior,　with　the　grain-boundary　atom　fraction　denoting　the　ratio　of　the　different　contributions.　The　change　of　the　Gibbs　free　energy　of　the　material　system　was　used　as　the　criterion　for　modeling　the　microstructure　evolution.　The　nanograin　growth　with　the　temperature　was　simulated　using　the　hybrid　model,　and　the　grain　growth　kinetics　of　the　nanocrystalline　metals　were　predicted.　The　simulation　result　that　the　rapid　discontinuous　grain　growth　takes　place　in　a　temperature　range　of　800-900　K　in　the　nanocrystalline　Cu　was　consistent　with　the　experimental　investigations　on　the　temperature-varying　grain　growth　behavior　of　nanocrystalline　Cu.　The　hybrid　model　is　applicable　to　predictions　on　the　thermal　stability　of　the　nanocrystalline　metals.