This study proposes LiF-BeF2-LiI as a molten salt for a liquid blanket system of a fusion reactor. Firstly, the melting point of LiF-BeF 2-LiI is measured as a function of the molar ratio of LiI. The experimental results confirmed that the melting point decreases to 398.2 °C when LiF:BeF2:LiI = 19:9.5:71.5, which is consistent with an earlier report. Experiments to evaluate the density and viscosity of LiF-BeF 2-LiI are also carried out. The experiments revealed that the density of LiFBeF2- LiI increases with the molar ratio of LiI, and the viscosity of LiF-BeF2-LiI (LiF:BeF2:LiI = 2:1:1) is somewhat larger than that of LiF-BeF2 (LiF:BeF2 = 2:1) but much smaller than that of LiF-BeF2 (LiF:BeF2 = 3:2). Monte Carlo numerical simulations using MVP-2.0 with JENDL-4.0 data library are conducted on the basis of the measured density to discuss the feasibility of a blanket system using LiF-BeF2-LiI. The numerical simulations demonstrate that LiF-BeF2-LiI can realize TBR>1.4, which is required for a fusion blanket system, with Be pebble layer and enriching 6Li.