In　order　to　develop　the　mixed　molten　salt　used　in　the　high　temperature　solar　thermal　power　generation,　the　mixed　molten　salts　were　prepared　by　adding　additives　to　lower　the　melting　point　and　improve　the　thermal　physical　properties　of　ternary　carbonates　with　different　mass　ratios.　The　melting　point,　initial　crystallization　point,　decomposition　temperature　and　specific　heat　were　tested　by　using　differential　scanning　calorimetry　and　thermogravimetry.　The　results　show　that　melting　points　of　6　kinds　of　ternary　carbonates　can　be　reduced　effectively　by　adding　additive.　The　melting　point,　the　initial　crystallization　point　and　the　decomposition　temperature　of　the　optimized　mixed　molten　salts　is　328℃,　359.3℃　and　810℃,　respectively.　By　using　the　fitting　equation　of　specific　heat,　the　heat　storage　cost　of　the　optimized　mixed　molten　salts　is　analyzed,　which　is　much　lower　than　that　of　ternary　carbonates.　©　2015,　Science　Press.　All　right　reserved.