Abstract: The freeze valve TMSR-FV1 functions as a normally closed shut-off valve in the secondary loop of the Thorium-based Molten Salt Reactor (TMSR). TMSR-FV2 is an improved version of TMSR-FV1, which heat transfer is enhanced by adding fins to the outer surface of freeze valve while keeping its size intact. In this paper, the Finite Element Method was used to make structural design and thermal analysis of TMSR-FV2. The effects of fin height, fin thickness and fin pitch on the cooling of molten salt in TMSR-FV2 under natural cooling conditions were studied. A finned freeze valve structure was proposed and compared with the experimental salt plug effect of TMSR-FV1 under natural cooling and different cooling flow conditions. The calculation results show that the proposed TMSR-FV2 effectively reduces the central molten salt temperature of the flat section to enhanc the salt plug of the freeze valve and realizes the passive closing function of the freeze valve within the scope of the research.