In　dynamical　evolution　of　structural　balance,　unbalanced　signed　networks　evolve　to　structurally　balanced　ones.　In　this　paper,　we　compute　the　least　number　of　sign　changes　in　the　evolution　of　structural　balance.　It　is　suggested　that　there　be　a　certain　bias　towards　flipping　positive　or　flipping　negative　signs.　The　number　of　flipped　signs　is　quantified　by　an　objective　function.　Moreover,　a　memetic　algorithm　is　proposed　to　optimize　the　objective　function.　Experiments　show　that　our　algorithm　is　efficient　and　effective　to　optimize　dynamical　evolution　of　structural　balance.　(C)　2015　Elsevier　B.V.　All　rights　reserved.