In　this　study,　expanded　graphite　(EG)　was　added　to　melted　stearic　acid　(SA)　by　the　melt　blending　method　to　prepare　SA/EG　composite　phase　change　material　(PCM)　with　different　ratios.　EG　with　ultra-high　porosity　and　large　specific　surface　area　can　effectively　adsorb　melted　SA　through　capillary　force　and　van　der　Waals　force.　The　results　showed　that　when　the　loading　amount　of　EG　was　12　wt.%,　almost　no　liquid　leakage　occurred　and　the　composite　showed　excellent　stability.　In　addition,　the　three-dimensional　network　structure　of　EG　interconnection　provides　an　efficient　heat　transfer　path　and　reduces　the　thermal　resistance　of　the　interface.　Therefore,　the　thermal　conductivity　of　the　composite　was　as　high　as　6.54　W　m−1　K−1,　which　was　19.179　times　higher　than　that　of　pure　SA.　Furthermore,　the　melting　enthalpy　and　melting　temperature　of　the　composite　were　163.35　J　g−1　and　67.08　°C,　respectively.　X-ray　diffraction　and　Fourier　transform　infrared　spectroscopy　shown　that　physical　interaction　instead　of　chemical　reaction　happened　between　EG　and　SA.　When　the　mass　fraction　of　EG　is　12　wt.%,　the　composite　PCM　shows　a　relatively　more　balanced　and　uniform　thermal　image　compared　with　SA,　and　the　heat　storage　rate　of　the　composite　PCM　was　about　2.3　times　of　SA,　and　the　heat　release　rate　was　3.1　times　of　SA.　In　addition,　the　composite　PCM　showed　excellent　thermal　stability,　chemical　stability,　and　cyclic　stability,　indicating　that　the　working　performance　of　the　composite　PCM　was　relatively　stable　within　the　temperature　range　of　100　°C.　©　2022　The　Author(s)