In this paper, a novel ternary eutectic salt Na2CO3-Li2CO3-LiF was designed and investigated for concentrated solar power (CSP). The FactSage software was used to predict the composition and eutectic point of Na2CO3-Li2CO3-LiF. The microstructure, thermophysical properties, and thermal stability of eutectic salts were experimentally measured using various analytical methods. With a mass ratio of 57%:32%:11%, the eutectic salt exhibited excellent thermal storage properties with a fusion enthalpy of 413 J/g and a melting point of 426.8°C. The excellent thermal stability of the eutectic salt was reflected by a weight loss of only 0.8% at 600°C.