The sensing and adsorption behaviors of Ru-doped MoS2 monolayer (Ru-MoS2) on the two main decomposition gases SO2F2 and H2S in SF6 insulated equipment were investigated based on the first-principles. Ru atoms were doped in sulfur vacancies to create Ru-MoS2 monolayer. The results show that the adsorption energy (Ead) of the SO2F2 and H2S adsorption systems are -1.52 eV and -2.11 eV, respectively, indicating that both systems are classified as chemisorption. Band structure(BS) and density of states(DOS) analyses further demonstrate the adsorption properties of both systems, and the gas adsorption sensing mechanism of single-layer Ru-MoS2 used in resistance gas sensor is described. In addition, the recovery time of Ru-MoS2 monolayer for the desorption of SO2F2 and H2S was explored theoretically at different temperatures, and the recovery time of SO2F2 adsorption system is 6.40 s at 598 K, demonstrating the recoverability of this novel material for gases at high temperatures. This study provides a theoretical basis for Ru-MoS2 to detect the two main decomposition gases SO2F2 and H2S in SF6 insulation equipment, which is essential to promote the stable operation of power systems.