Display omitted •The Rh-doping behavior on BN monolayer has a good doping effect.•Rh-BN monolayer exhibits ideal adsorption and sensing properties, selectivity for SF6 decomposed gases.•The electronic behavior and sensitivity analysis help to understand mechanism and reflect the excellent applicability. The SF6 decomposed gases sensor is crucial for detecting insulation condition of electrical equipment. To study applicability of metal-doped two-dimensional (2D) nanomaterials for gas sensors, density functional theory (DFT) calculations based on first-principle theory were used for investigating adsorption properties, sensitivity and electronic behavior. In this study, Rh-doped h-BN (Rh-BN) monolayer was first proposed to analyze adsorption of typical SF6 decomposed gases, including H2S, SO2, SOF2, SO2F2. The stable structure of Rh-BN monolayer was studied by four possible sites. The binding energy (Eb) of stable structure is −1.204 eV. Meanwhile, the adsorption energy (Ead) and sensitivity of SF6 decomposed gases show that Rh-BN monolayer has ideal adsorption and sensing properties than other materials. Moreover, the analysis of density of state (DOS) and band structure illustrate the sensing mechanism and further prove the applicability of Rh-BN monolayer for SF6 decomposed gases. The above calculations and analysis would be significant to explore Rh-BN monolayer as a novel SF6 decomposed gases sensor for electrical equipment insulation.