SO2F2 plays important roles in the gas-insulated switchgear (GIS) equipment because it has been widely used as the characteristic gas in discharge diagnostics.However, the mechanism for the formation of SO2F2 is not clear [1].It was proposed that the hydrolysis of SOF4 can produce SO2F2 via SOF4 + H2O =SO2F2 + 2HF in the gas-phase but the overall rate constant was as low as (1.0±0.3)×10-21 cm3/s[2].The potential energy surface of the hydrolysis of SOF4 together with the water-catalyzed mechanism to form SO2F2 is calculated herein using various ab initio methods (Figure 1).Temperature-dependent rate constants are presented as well.