The　heat　storage　performance　and　phase　change　stability　of　mixed　phase-change　materials　consisted　of　stearic　acid　and　Na2HPO4·12H2O　was　studied　by　means　of　Fourier　transformation　infrared　spectrum　analyses　and　DSC.　The　specific　heat　capacity　of　mixed　materials　was　also　determined　experimentally.　The　results　show　that　all　absorption　peaks　of　the　functional　groups　and　chemical　bonds　of　stearic　acid　still　exist,　which　suggests　that　stearic　acid　and　Na2HPO4·12H2O　crystal　materials　have　good　phase　change　stability　and　chemical　compatibility.　Mixtures　of　these　two　materials　can　overcome　the　disadvantage　of　both　the　sub　cooling　of　Na2HPO4·12H2O　and　the　low　specific　heat　capacity　of　stearic　acid　in　order　to　complement　each　other　on　the　basis　of　organic/inorganic　characteristics.