The adsorption property of small toxic gaseous molecules (SO2, SO3, H2S, and N2O) with metal/hexa‐vacancy defective graphene (denoted as HDG‐M, M: Fe2+, Co2+, Ni2+, Cu2+, and Zn2+) was determined by density functional theory. The results of these calculations show that the Fe2+ion has the best and Cu2+the worst absorption ability to capture all of the above toxic gases with selected adsorption orientation. These results can provide useful information for the application of the designed HDG‐M adsorbents in food science and ecosystem monitoring. Predict the binding of toxic gases with metal ions ‐ hexa‐vacancy defective graphenes (HDG). HDG‐Fe(II) and HDG‐Cu(II) have the best and worst abilities to capture SO2, SO3, H2S , and N2O, respectively.