The　operational　flexibility　of　coal-fired　power　plant　is　very　important　for　the　integration　of　large-scale　renewable　energy　to　the　grid.　In　order　to　increase　the　operational　flexibility　of　coal-fired　power　plant,　a　600　MW　subcritical　coal-fired　power　plant　was　selected　as　research　example　to　analyze　the　influence　of　steam　extraction　parameters　and　operation　load　by　simulation.　A　novel　main　steam　extraction　system　was　proposed　to　adjust　the　power　output　under　the　low　load　period.　The　sensible　and　latent　heat　of　the　extracted　steam　was　stored　in　molten　salts　and　phase　change　materials,　respectively,　during　the　load　reduction　process.　While　the　stored　heat　was　reused　again　to　heat　the　feed　water　and　condensate　water　during　the　load　raising　process.　The　50%　rated　load　(300.03　MW)　of　the　unit　was　used　as　the　research　benchmark　to　further　adjust　the　load.　The　results　show　that　the　proposed　steam　extraction　system　can　improve　the　operational　flexibility　of　coal-fired　power　plant.　The　power　output　can　be　reduced　to　204.51　MW　from　300.03　MW　when　the　main　steam　extraction　mass　flow　rate　is　250　t/h　during　the　load　reduction　process.　The　sensible　heat　storage　power　factor　and　the　operation　load　of　the　unit　can　affect　the　power　output　increment　of　coal-fired　power　plant　during　the　load　raising　process.　Under　the　condition　of　the　maximal　sensible　heat　storage　power　factor　is　0.2462,　the　power　output　can　be　increased　to　325.47　MW　from　300.03　MW　when　the　bypassed　feed　water　mass　flow　rate　of　251　t/h　was　heated　by　the　stored　heat　during　the　load　raising　process.　Using　such　operation　model,　the　coal-fired　power　plant　can　achieve　the　maximum　deep　peak　shaving　time　of　8.4　h/d,　and　its　equivalent　thermal　efficiency　is　increased　by　2.28%.　With　the　same　stored　thermal　energy　to　heat　the　bypassed　feed　water　of　308.65　t/h,　the　power　output　can　be　increased　to　394.2　MW　from　360.07　MW　(60%　rated　load)　at　the　same　sensible　heat　storage　power　factor　of　0.2462　during　the　load　raising　process,　and　the　coal-fired　power　plant　can　achieve　the　maximum　deep　peak　shaving　time　of　9.86　h/　d　with　its　equivalent　thermal　efficiency　increase　of　2.55%.　The　results　show　that　the　proposed　steam　extraction　method　can　make　the　unit　operate　in　the　lowest　stable　load　and　provide　a　wider　renewable　energy　access　space　below　the　minimum　stable　load.　The　research　provides　a　theoretical　guidance　for　the　flexibility　design　of　coalfired　power　plant,　especially　suitable　for　the　large-scale　renewable　energy　access　to　the　grid　in　China.