Methanol steam reforming (MSR) is a potential method for producing hydrogen in situ. Finding excellent catalysts to improve reaction activity and CO₂ selectivity is crucial. In this study, we used density functional theory (DFT) methods and the CP2K software package to investigate the mechanism of the MSR reaction on dual-atom catalysts of PtZn/TiO₂ and PdZn/TiO₂. The results showed that the most favorable reaction paths on these two catalysts are the same, namely CH₃OH→CH₃O→CH₂O→CH₂OOH→CHOOH→CHOO→CO₂, in which the rate-determining step is CH₂O+OH→CH₂OOH with reaction barriers of 1.17 eV on PtZn/TiO₂ and 1.29 eV on PdZn/TiO₂, respectively. The reported PtZn/TiO₂ and PdZn/TiO₂ catalysts show improved activity compared to pure metal or corresponding alloy catalysts. The synergistic effect between metal atoms and the surface of TiO₂ supports as well as the role of Zn atom doping were discussed. This work provides a new perspective for the design of atomic-level catalysts for the MSR reaction.