Two-dimensional transition metal disulfides (TMDs) has attracted considerable attention due to its excellent physicochemical properties. In order to detect the SF6 decomposition products, transition metal Pt cluster doping was chosen to enhance the adsorption property of intrinsic WSe2 monolayer. The adsorption of SO2, SOF2 and SO2F2 on Ptn (n=1–3) doped WSe2 monolayer is studied based on the first-principle calculation. The adsorption energy, charge transfer, and density of states of the interaction between the target gas molecules and Ptn-WSe2 were studied. The calculation results showed that Pt3 doping dramatically enhances the adsorption of WSe2 to SO2 and SOF2 and SO2F2 molecules. Meanwhile, electrons transfer from Ptn-WSe2 surface to these three kinds of target gas molecules, reducing the conductivity of the adsorption system in different degrees. The results of this study not only have important significance for explaining the sensing mechanism of Ptn-WSe2 adsorption to SF6 gas decomposition products, but also provide a potential material for further development of gas sensing sensors.