In the maintenance of transmission lines, prompt detection and repair of electrical equipment faults can greatly reduce the losses of public property. Hence, the development of a highly sensitive detection device for transformer oil fault gases (H2, CH4, CO, and C2H2) is of significant importance. This study investigates the adsorption behavior and sensing characteristics of TiO2 and Ag2O-doped GeTe monolayers on transformer oil fault gases using first principle calculations. The results indicate that doping TiO2 and Ag2O enhances the conductivity of the GeTe monolayer by 16.8% and 14.9%, respectively. However, in comparison to TiO2, Ag2O significantly increases the adsorption energy of the GeTe monolayer for the four gases: H2 (301%), CH4 (252%), CO (299%), and C2H2 (249%). The suitable adsorption energy enables the Ag2 O-doped GeTe monolayer to exhibit good sensitivity and allow for gas desorption from the substrate at high temperatures, potentially addressing the industrial issue of recovery and utilization of sensing materials. These findings provide a theoretical foundation for the design and application of resistance-based chemical sensors used to detect transformer oil decomposition gases.