Abstract: For the energy analysis problem of large and complex structures，SAP 2000 was used to established a model of the enlarged-base twin-tower with connective structures，and elastic energy analysis was carried out by using the corresponding program of MATLAB and SAP 2000，and gave the relationship between the structural energy response and the energy response of a single degree of freedom system was given in order to carry out a structural vibration modal decomposition energy analysis and build an energy response spectrum． It was studied the elasticplastic energy response of the structure under the action of three-dimensional seism，whose result was compared with that of the case without connected structures． The studies showed that the vibration modal decomposition energy analysis method could quickly，efficiently estimate the energy response of structures，and the aseismic performance of a connecting structure was better than non-connected structure in a certain extent．