In this study, the adsorption of waste gases (CH4, H2S, CO) generated during the extraction, processing, and utilization of natural gas on TM atom (Sc, V, Cr, Mn)-modified HfSe2 surfaces were analyzed using Density Functional Theory (DFT) calculations. Initially, the doping effects of the four TM atoms were examined, followed by a detailed investigation of the adsorption of these three gases in terms of adsorption energy, band structure, density of states (DOS), charge transfer, and recovery time. Among the TM atoms, Sc doping was found to be the most favorable due to its highest adsorption energy. However, in subsequent gas adsorption processes, it was observed that V and Mn-modified HfSe2 surfaces exhibited better adsorption performance for H2S and CO. Furthermore, it was discovered that at high temperatures, V-HfSe2 can function as a gas sensor for CO, while at room temperature, V-HfSe2 and Mn-HfSe2 can serve as high-precision real-time monitoring sensors for H2S and CO, respectively.