The stability of underground structures is a complex and difficult issue due to changes in rock and soil types, geological structure, regional stress conditions, excavation stages, and the creation of underground space from one location to another. Therefore, it is necessary to investigate the stability status of the structure in question by using different stability analysis methods, comparing the results obtained from them, and also using appropriate engineering judgment. The purpose of this research is to analyze the stability of Tunnel A of Qom Metro under the influence of static and dynamic loads. For this purpose, the studied environment has been modeled using Plaxis finite element software and using the plane strain theory with 15-node elements. By performing the geotechnical study of the area and considering the desired tunnel cross-section, it was possible to change the structural characteristics as well as the seismic environment. The results show that by increasing the thickness of the initial tunnel lining, the applied displacements decreased by 0.5% and the applied forces increased. It should be noted that by increasing the thickness of the tunnel lining from 20 cm to 35 cm, the tunnel floor has been decreased by about 100%, but this difference is less in other studied points.