The safety against seismic loads of the dams existing at present and the design of new earthquake-resistant dams is under rigorous research. The designs of the earthquake-resistant dams along with the evaluation for safety of the existing dams depend upon the reliable analytical procedure that can determine the stresses and deformations induced by the earthquake. Therefore, this study is carried out to perform the modal analysis, study the influence of hydrostatic forces, and also to determine the effect of dynamic loads on the dam with rigid and flexible foundation by using ABAQUS. In this study, modal, static, and dynamic analysis of Koyna dam located in Maharastra, India was performed by using ABAQUS. Dynamic analysis of the dam is done under two conditions: dam with a rigid base and dam with a flexible base. North–South Component of the El Centro data was used for the dynamic analysis of the Koyna Dam. The crest of the dam undergoes a displacement of 0.016 m in case of flexible foundation which is higher compared to the displacement of the crest without the dam with rigid foundation, which is 0.0107 m. Major principal stress and shear stress value is found to be higher in case of flexible foundation as compared to rigid foundation of the dam. In case of rigid foundation, maximum displacement is found within the crest of the dam for all the time steps due to dynamic load, whereas Maximum displacement observed within the center part of the dam for the time steps of 0.6 and 0.8 s and at the base of the dam for the 1 s time step due to dynamic load in case of flexible foundation. The major principal stress of the dam is found to be lower (1.04E+09 N/m²) in case of flexible foundation as compared to the rigid foundation (1.55E+09 N/m²). The shear stress of the dam is found to be higher in case of flexible foundation (6.95E+09 N/m²) as compared to the rigid (5.28E+08 N/m²) foundation.