To　describe　the　thermal　stability　of　the　nanocrystalline　solid　solution　with　weak　segregation　such　as　Cu-Zn　system,　we　developed　a　hybrid　model　combining　the　first　principles　calculation　and　thermodynamic　evaluation.　The　dependence　of　the　solute　segregation　behavior　on　the　solute　concentration,　grain　size　and　temperature　were　demonstrated.　We　found　that　the　segregation　energy　does　not　change　with　the　solute　concentration　monotonically.　At　a　constant　solute　concentration　and　a　given　temperature,　a　nanograin　structure　can　remain　stable　if　the　initial　grain　size　is　kept　in　a　critical　range.　The　model　predictions　were　confirmed　by　the　experimental　measurements　that　a　state　of　steady　nanograin　growth　can　be　achieved　by　designing　a　certain　solute　concentration　and　a　proper　initial　grain　size.　©　2017　Trans　Tech　Publications,　Switzerland.