Information on SF6 decomposition components can be detected using gas-sensitive sensor methods to assess the operational status of GIS equipment and detect the insulation defects early. Metal-doped SnP3 monolayer has good adsorption properties, which makes it promising for gas detection applications. Based on the first-principles, the parameters of adsorption energy, density of states, energy gap and desorption time of the system after the adsorption of SO2, H2S, SOF2 and SO2F2 by Pd-SnP3 monolayer were calculated and analyzed to explore the possibility of using this material for gas sensors. The results show that, in terms of adsorption performance, Pd-SnP3 monolayer only chemisorb SO2F2. Combined with the results of density of states, differential charge density and transfer charge analysis, it is verified that the adsorption of SO2F2 is significantly better than that of SO2, H2S and SOF2. In terms of sensing characteristics, only the adsorption of SO2F2 causes significant change in the energy gap of the system, and desorption of SO2F2 from the Pd-SnP3 monolayer surface rapidly occur at temperature of 398 K and above. Therefore, the Pd-SnP3 monolayer has the potential to become a gas-sensitive material for the detection of SO2F2 for its high selectivity and detectability to SO2F2. This study provides a theoretical basis for the application of Pd-SnP3 monolayers in the field of gas-sensitive materials.