The capability of pure and Fe-doped silicon carbide nanosheets (Fe-SiCNSs) for adsorbing of ozone, sulfur dioxide and nitrogen dioxide molecules were scrutinized by means of density functional theory calculations. The molecular electrostatic potential, adsorption energy and charge transfer of these gas molecules on pure and Fe-SiCNSs are studied. The high negative adsorption energy values show that these gas molecules are desirably chemisorbed on the surface of Fe-doped silicon carbide nanosheets, with a more adsorption capability compared to pure SiCNS. The calculation shows that SiCNS is a semiconductor with a band gap of 2.49 eV. After the adsorption of O3, SO2 and NO2 molecules on the pure and Fe-SiCNSs, the energy gap of the sheets are decreased, especially in adsorbed sulfur dioxide on pure SiCNS with 0.67 eV. This investigation shows that SiC based nanomaterials can be helpful for controlling and capturing of harmful gases.