Fused salt system for dry post-treatment of oxide spent fuel

The invention discloses a fused salt system for the dry post-treatment of an oxide spent fuel. In the fused salt system, uranium tetrafluoride is used as a fused salt main body, and a perfluoride mixture of uranium pentafluoride or uranium tetrafluoride, which occupies 0.1-10 percent of the total mass of the fused salt, is added. The fused salt system not only can be used for dissolving the oxidespent fuel in the fused salt, but also can avoid strong complex anions in the fused salt from seriously corroding equipment.