Abstract: The seismic analysis on integral reactor system was performed with TSV code which is applicable for calculating the large-scale finite element model.Two different models were calculated respectively.Damping effect was considered in one model,and nonlinear contact in the other one.The number of freedom degree of either model was more than twenty millions.The typical results of time-history response to Operational Basis Earthquake（OBE） excitation were given based on these two models.The results of this paper are larger than those with two-dimensional simplified FEM,and the reasons of this phenomenon were presented.The feasibility of seismic analysis on integral large-scale threes-dimensional finite element model under existing hardware condition was demonstrated,so a new approach to dynamic analysis on integral complex equipments or systems in nuclear power plant was explored.