[4]. In this paper, two dams of height below the 100 m that is 70 m and 90 m and dam of height above 100 m that is 110 m have been analyzed by using the response spectrum and time history analysis, based on IS codes and also to cross check whether dynamic analysis is necessary or not for the dam of height below 100 m. And the results obtained are compared eventually to determine the structural performance of concrete gravity dam. Response spectrum and time history analysis play an extraordinary role. In time history analysis time acceleration as an input data with acceleration with respect to time. Time history analysis provides the various mode shapes and direction of structure which varies as per specified time-acceleration function and these mode shapes varies as dynamic structural response under various loading. After the dynamic analysis it can be easily predicted whether the structure will survive or not under the effect of seismic vibration. The details of the study and its result are described briefly in the following section of the paper.