Abstract: Sulfate is quite crucial to influence Tc/Re volatilization during nuclear liquid waste vitrification, but the mechanism of the effect is not yet clear. In this paper, the simplified SiO₂-KReO₄-K₂SO₄ system was used to study the effect of sulfate on Re volatilization during vitrification, and the heat-treated samples were characterized with XRD, TG-DSC and ICP-AES. The results show that sulfate hardly effects Re volatilization, when the mass ratio of Re to S ≥1.80; whereas, when the mass ratio of Re to S <1.80, sulfate promotes Re volatilization and reduces the Re volatilization temperature.