Abstarct: Abstract: The importance of identifying unique gases in the environment is very important considering today's highly polluted world and the existence of global warming. The main factors in air pollution are nitrogen oxides (NOX) and carbon oxides (COX). Among the nanomaterials used in the construction of sensors in recent years, graphene has gained attention due to its unique properties. The challenges in graphene led researchers, inspired by the properties of graphene, to look for alternative capabilities. In the meantime, Stanene, the newest two-dimensional structure of a graphene-like honeycomb, shows a stronger interaction than gas molecules due to its unique properties and characteristics. In this research, for the first time, the potential of NOX and COX gas nanosensors baxsed on armchair stanene nanoribbons with a width of 6 and a width of 8 has been studied. For this purpose, density functional theory (DFT) has been used to study the electronic structure of the ground state, and the combination of non-equilibrium Green's function (NEGF) and DFT has been used to investigate the transport properties. The band structure results show that the nanoribbon with a width of 6 is a semiconductor with a direct band gap of 0.376 electron volts and a nanoribbon with a width of 8 is a semiconductor without a band gap. The results of absorption calculations include important parameters such as absorption configurations, stable and equilibrium states, structural properties, charge transfer, recovery time, sensitivity and electronic properties including band structure and density of states as well as transport properties including transfer spectrum and curve. It is current-voltage. We first performed these analyzes on pure stannane hydrogen nanoribbons with widths of 6 and 8. The results indicated that among the studied gases, the strongest interactions with the surface of nanoribbons are related to nitrogen oxides (NOX), and the weakest interactions are related to carbon oxides (COX). Also, by comparing the results, the stannene nanoribbon with a larger width (8) shows a relatively better response to the investigated gases compared to the smaller width (6). The current-voltage results show that the current increases after the absorption of all molecules on the 6-width nanoribbon and decreases on the 8-width nanoribbon, and the largest and smallest changes are related to the absorption of NO and CO2 molecules, respectively. In order to improve the electronic properties of the 8-width nanoribbon for CO gas sensing, we investigated the effect of doping the nanoribbon with N and B atoms before and after absorption. The results showed that this structural engineering causes the opening of the band gap and the adsorption of CO is much stronger, and then the sensing properties are improved. In the end, we investigated the effect of defects in the dangling bonds on the nanoribbon with a width of 6 and studied the adsorption of NO on the edge of the nanoribbon before and after the defect. The results indicated that the presence of possible defects on the edge of the nanoribbon not only does not reduce its sensing but also strengthens it. Finally, our results recommend pure stanene nanoribbons and doped with N and B atoms as promising new materials with high potential for sensing the studied gases.