With　the　fast　development　of　concentrating　solar　power,　a　form-stable　composite　material　containing　ternary　carbonates　(K2CO3-Li2CO3-Na2CO3)　as　high　temperature　thermal　energy　storage　materials　and　ceramic　MgO　as　supporting　material　is　proposed　to　prevent　molten　salts　from　leakage　and　the　relevant　corrosion.　Using　cold　compression　and　mixed　sintering　method,　ternary　carbonates　can　be　embedded　and　distributed　uniformly　in　intervals　and　pores　between　MgO　particles.　There　aren＇t　chemical　reactions　between　carbonates　and　MgO　during　sintering　at　a　high　temperature.　Among　of　samples　with　different　mass　ratios,　the　composite　material　containing　50　wt%　ternary　carbonates　gives　the　highest　mechanical　strength.　Specific　heat　capacity　and　latent　heat　of　the　composite　material　with　an　optimal　ratio　of　5:5　can　be　up　to　1.48　J/g　K　(450-600　degrees　C)　and　158.7　kJ/kg,　respectively.　It　has　a　relative　low　melting　point　(386.4　degrees　C),　and　it　hasn＇t　obvious　mass　degradation　even　at　1000　degrees　C　due　to　the　strong　adsorption　of　carbonates　in　intervals　and　pores　between　MgO　particles.　Moreover,　the　composite　material　shows　a　good　thermal　cycling　stability　after　100　cycles.　The　resulting　form-stable　composite　material　can　provide　a　wider　service　temperature　range　and　a　higher　thermal　storage　density　based　on　the　utilization　of　latent　heat　and　sensible　heat　of　molten　salts.