Abstract: Using non-equilibrium Green's function combined with density functional theory, the electronic properties and transport properties of four systems of penta-graphene (PG), CO/PG, Fe-PG and CO/Fe-PG were calculated in order to explore the sensitivity of PG and Fe-PG to CO gas molecules from first principles. Firstly, Fe-PG has a large amount of charge transfer during the process of adsorbing CO gas molecules, and it has a small adsorption energy which indicates the strong interaction between it and CO. The results also reveal that the Fe-PG system is more sensitive to the adsorption of CO gas molecules. Secondly, the densities of states (DOS) of the four systems are calculated. It is found that the DOS between the Fe-PG and CO/Fe-PG systems have a large change, which further shows that there is a strong interaction between Fe-PG and CO, and the Fe-PG system is sensitive to the adsorption of CO gas molecules. Finally, the transport properties are explored and it is found that the sensitivity of Fe-PG to CO gas molecules is two orders of magnitude higher than that of the original PG. Further, the transmission spectrum under zero bias further proves that Fe-PG is a good sensing material for detecting CO gas molecules. This research work demonstrates that the proper introduction of Fe atom dopants into the PG structure system can greatly improve the sensing properties of PG to CO molecules.