Abstract: From the version of radiochemistry, this paper introduced molten salt reactor (MSR) and its advantages in the application of thorium-uranium fuel cycle briefly. Then three radiochemical research fields related to MSR were stated: fuel supply, reprocessing for irradiated fuels, and monitoring and diagnosis during the reactor operation. In the fuel reprocessing, a novel pyroprocessing technical roadmap, similarly to AIROX flowsheet reported in references, was recommended, and its advantages and important value in on-line fuel processing of MSR were illustrated. Due to great amount of issues on the chemistry and radiochemistry occurred in MSR operation, MSR is just like a “chemical reactor”, thus radiochemical monitoring and diagnosis have a significant meaning to the operation of MSR. It is pointed out that a new discipline branch of radiochemistry, i.e. the molten salt reactor chemistry, aiming to the monitoring and diagnosis of MSR is formed. At the end of the paper, some suggestions that radiochemistry researchers should keep in mind during the development progress of MSR were advised.