With　the　depletion　of　fossil　fuel　energy　and　both　the　slow　development　and　low　utilization　rate　of　new　eco-friendly　energy,　finding　new　ways　to　efficiently　store　energy　has　become　a　research　hotspot.　Presently,　polyethylene　glycol　(PEG)　is　an　excellent　heat　storage　material,　but　it　is　a　typical　solid-liquid　phase　change　material　(PCM)　with　a　risk　of　leakage　during　phase　transition.　A　combination　of　wood　flour　(WF)　and　PEG　can　effectively　eliminate　the　risk　of　leakage　after　the　melting　of　PEG.　However,　WF　and　PEG　are　both　flammable　materials,　which　impedes　their　application.　Therefore,　it　is　of　great　significance　to　expand　their　application　by　forming　composites　from　among　PEG,　supporting　mediums,　and　flame-retardant　additives.　This　will　improve　both　their　flame　retardancy　and　phase　change　energy　storage　performance,　and　will　also　lead　to　the　preparation　of　excellent　flame-retardant　phase　change　composite　materials　with　solid-solid　phase　change　characteristics.　To　address　this　issue,　ammonium　polyphosphate　(APP),　organic　modified　montmorillonite　(OMMT),　and　WF　were　blended　into　PEG　in　specific　proportions　to　prepare　a　series　of　PEG/WF-based　composites.　Both　thermal　cycling　tests　and　thermogravimetric　analysis　results　demonstrated　that　the　as-prepared　composites　had　good　thermal　reliability　and　chemical　stability.　In　addition,　during　differential　scanning　calorimetry　tests,　the　PEG/WF/8.0APP@2.0OMMT　composite　presented　the　highest　melting　latent　heat　(176.6　J/g),　and　its　enthalpy　efficiency　reached　more　than　98.3%.　The　PEG/WF/8.0APP@2.0OMMT　composite　also　exhibited　superior　thermal　insulation　performance　when　compared　to　the　pure　PEG/WF　composite.　Furthermore,　the　PEG/WF/8.0APP@2.0OMMT　composite　exhibited　a　significant　50%　reduction　in　peak　heat　release　rate　as　a　result　of　the　synergistic　effect　between　OMMT　and　APP　in　the　gas　and　condensed　phases.　This　work　offers　a　useful　strategy　for　the　fabrication　of　multifunctional　phase-change　material,　which　is　expected　to　broaden　its　industrial　applications.