Abstract: In recent years，the safety issues caused by the thermal runaway phenomenon of lithium iron phosphate energy storage batteries have attracted great attention.Effective detection of the characteristic quantity of thermal runaway gas is of great significance for evaluating its operating status，among which CO is an important characteristic gas for overcharging and thermal runaway of lithium iron phosphate energy storage batteries.Based on first principles，intrinsic CeO2，Pt doped modified CeO2 models，and CO absorption models are built.The modification mechanism and gas adsorption mechanism of CeO2 based gas sensing materials are analyzed from the aspects of adsorption energy，charge transfer，energy band，and density of states.Our results show the absorption energy of CO—CeO2 is only－0.202 8 eV，exhibiting weak physical absorption whereas Pt—CeO2 exhibits excellent chemical absorption performance for CO，with a corresponding charge transfer value of 0.029 0 eV.After doping with Pt，the energy band of CeO2 decreases from 1.933 eV to 1.259 eV，and the absorption distance for CO is cut from 3.183?to 2.021?.Therefore，Pt doped modified CeO2 serves as a candidate for CO detection sensors for thermal runaway characteristic gases in lithium iron phosphate batteries，providing theoretical support for the development of highly sensitive and low power thermal runaway characteristic gas detection sensors for lithium iron phosphate energy storage batteries