Abstract: A method and a device for preparing MoF6 based on plasma activation of SF6. The method includes the following steps: S1, filling a discharge area of a plasma reactor with molybdenum powder; S2, introducing an inert gas and an SF6 gas into the discharge area of the plasma reactor, where the inert gas is ionized into plasma, and the SF6 gas is ionized into fluorine atoms and low-fluorine sulfides after being activated by the plasma; and S3, generating an MoF6 gas and sulfur elements through reaction of the fluorine atoms and the low-fluorine sulfides with the molybdenum powder.