Randomness is one of the important characteristic factors of seismic load，which can not be ignored in seismic design.In this paper，Jin'anqiao gravity dam is selected as the research object to study the different failure modes of the dam under different seismic wave loads，the failure characteristics and dynamic response of gravity dams under different types of seismic loads are discussed，which can provide basis for seismic design of gravity dams.The results show that the failure modes of gravity dams under different seismic wave loads are obviously different，the amplitude of dam displacement and the speed of damage evolution are closely related to the input seismic load parameters.Therefore，affected by the randomness of seismic load，the potential vulnerable area of the structure can not be determined only by a single seismic wave analysis，and the research on the correlation between the frequency spectrum characteristics of seismic load and the dynamic response of the structure needs to be strengthened.