Based　on　first-principles　calculations,　the　structural　stability　and　temperature　effect　in　ScX　(X=S,　Se　and　Te)　compounds　are　studied　with　three　typical　structures　of　B1　(NaCl-type),　hcp　(NiAs-type)　and　beta-hcp　(inverse　Li2O2-type).　Their　dynamic　stability　has　been　verified　using　phonon　mode　analysis　and　molecular　dynamics　simulations.　From　the　total　energy　calculations,　we　find　that　the　most　stable　ground　state　structures　are　B1　for　ScS,　and　hcp　for　ScSe　and　ScTe,　respectively.　Moreover,　structural　stabilities　at　finite　temperature　are　studied　with　the　combination　of　phonon　dependent　dynamics　analysis　and　first-principles　calculations,　which　reveals　a　phase　transition　from　hcp　to　B1　in　ScSe　around　230　K　and　a　phase　transition　from　hcp　to　beta-hcp　in　ScTe　around　460　K,　in　accordance　with　experimental　findings.　The　energy　barrier　and　pathway　along　the　phase　transformation　from　hcp　to　beta-hcp　ScTe　are　also　calculated　and　analyzed　by　the　solid-state　nudged　elastic　band　method.　(C)　2020　Elsevier　B.V.　All　rights　reserved.