36　kinds　of　mixed　carbonate　molten　salts　were　prepared　by　mixing　potassium　carbonate,　lithium　carbonate,　sodium　carbonate　in　accordance　with　different　proportions.　The　data　of　melting　point　and　latent　heat　are　measured　by　the　analysis　of　DSC　curves　of　36　kinds　of　salts,　which　show　that　the　majority　of　ternary　carbonate＇s　melting　points　are　close　at　around　400　A　degrees　C.　24　kinds　of　eutectic　molten　salts　were　selected　among　36　kinds　of　molten　salts.　With　high　latent　heat,　ternary　carbonate　salt　has　the　potential　to　be　employed　for　phase　change　thermal　storage.　The　costs　for　phase　change　thermal　storage　of　24　kinds　of　carbonate　salts　are　calculated.　Finally,　13　kinds　of　ternary　carbonate　salts　with　lower　cost　for　phase　change　thermal　storage　are　recommended,　where　there　are　6　kinds　of　mixed　carbonates　have　the　considerably　larger　latent　heat　of　melting.