Double　reheat　is　a　potential　technique　to　increase　the　efficiency　of　coal-fired　power　plants.　Large　penetration　of　renewable　power　requires　coal-fired　power　plants　to　operate　flexibly.　The　thermal　inertia　of　a　double-reheat　boiler　is　extremely　high　due　to　its　complicated　flow,　strong　coupling　and　numerous　devices,　which　seriously　restrict　the　operational　flexibility　of　double-reheat　coal-fired　power　plants.　In　this　study,　dynamic　simulation　models　and　temperature　control　systems　of　a　double-reheat　boiler　are　developed　via　GSE　software　and　then　validated　to　understand　the　heat　storage　change　law.　An　improved　control　model　considering　heat　storage　changes　is　proposed.　The　flexibility　of　original　and　improved　control　strategies　is　compared.　It　turns　out　that　steam　temperatures　in　the　boiler　system　with　the　original　control　exceed　the　allowable　ranges　when　the　load　cycling　rate　is　1.5%　Pe0　min(-1).　By　contrast,　steam　temperatures　in　the　boiler　system　with　the　improved　control　remain　within　the　allowable　ranges　when　the　load　cycling　rate　is　3.0%　Pe0　min(-1).　The　response　time　with　the　improved　control　is　shorter　than　that　with　the　original　control.　This　study　is　expected　to　provide　a　detailed　reference　for　improving　the　flexibility　of　double-reheat　power　plants.　(C)　2020　Elsevier　Ltd.　All　rights　reserved.