In recent years, in reaction to the increasingly urgent usage of urban spaces, the excavation of underground spaces has been developed. One of the most challenging projects faced by tunnel engineering is construction of subway stations as large underground spaces in shallow ground and soft surrounding soil in urban areas. Subway stations are of those underground spaces that have a great importance in development of urban traortation. In attention to excavation of these underground spaces in urban areas with weak formations, stability analysis and support design of such underground spaces in construction stages and long term stability must be evaluated. In this thesis, Naghshe Jahan Square Subway Station that is located in Isfahan, Iran, has been simulated by FLAC3D geomechanical finite difference method (FDM). This station is located under important historical structures, therefore the ground displacement induced by excavation of the Naghshe Jahan Square subway station and the settlement on the ground surface are very important. Many of such problems are affected by selective excavation method. For these reasons, in this thesis, different underground excavation methods and their construction methods have been studied and evaluated. The best excavation method can be selected in different geology conditions and available equipments with investigation and comparison between different excavation methods such as sequential excavation method, cut and cover method, concrete arch pre-supporting system, enlargement shield tunneling method, multi-face shield construction method, microtunneled arch method and large-diameter curved pipe roofing method that have been investigated in this study. Sequential excavation method, sequential excavation method with middle columns and large-diameter curved pipe roofing method have been used in this thesis and the results that derived from numerical analysis of these methods are compared. For stability analysis of Naghshe Jahan Square Subway Station, different support systems have been evaluated using different stability criteria and then the appropriate support system has been selected. For excavation of urban underground spaces in soft ground beneath water table, there are some methods. As such of these methods we can mention; dewatering, chemical consolidation and grouting, freezing, closed face tunneling machines and compressed air that all of these methods have some problems and benefits. About compressed air method, this method is still frequently employed and it is important that engineers understand its effect upon both labour force and the environment in orde to minimize its adverse effects like hazard to health of workers at high pressures, risk of damage to old structures and risk of sudden decompressions, and about ground freezing problems we can expre surface access required, causes damaging heave of surface in some soils and this method is very expensive to maintain freeze. The fact that our cities are often sited on flood plains means that soft ground tunneling techniques are frequently employed, but the presence of underground water table means that special techniques must be adopted to maintain stability of the ground during the construction; hence compressed air and ground freezing techniques have been utilized in simulation of subway station. Numerical analysis results have been compared with the permissible settlemet of surface structures and eventually the appropriate excavation methods and support systems have been selected.