Abstract: Renewable energy sources have gained significant attention due to the increasing energy consumption and environmental issues. Biomass, as the only renewable carbon source, has attracted significant interest for its efficient thermochemical conversion. Through thermochemical conversion technology, the macromolecules of biomass can be effectively directed towards the conversion into small molecular gases. Owing to their exceptional thermal conductivity, solubility, and high catalytic activity, molten salts have a broad array of applications as heat transfer fluids and energy storage media. In biomass conversion, molten salts exhibit considerable advantages, effectively enhancing both the yield and quality of syngas, significantly reducing the production of tar and char, and minimizing emissions of gaseous pollutants and particulate matter. Furthermore, molten salts can effectively store solar energy, providing the necessary heat for the thermochemical conversion of biomass The review focused on the characteristics of different types of molten salts, with particular emphasis on the excellent melting points and stability of alkali metal carbonates, as well as their significant advantages in enhancing the quality of the three-phase products. The research progress related to the thermochemical conversion of biomass in molten salt-mediated is explored, with a detailed analysis of the catalytic mechanisms of molten salts on biomass pyrolysis and gasification provided. The influence mechanisms of molten salt cations and anions on the reaction pathways and product distribution with the thermochemical conversion of biomass are investigated. Moreover, the progress of process technology for biomass thermochemical conversion in molten salt-mediated are summarized, noting that although the technology has made some advancements at the laboratory scale, there is still a considerable gap to industrial application. In addition, the current status of process simulations for biomass thermochemical conversion in molten salt media is outlined, potential challenges in achieving large-scale application are discussed, and insights into future research directions are provided.