In this paper, twin tower buildings with large bases were studied. The FEM models with connecting and without connecting buildings were established separately. The dynamic characteristics of both models were studied. The influences of connection over the structure vibration mode and natural vibration period were discussed. The dynamic responses of models were also analyzed by time-domain buffeting analysis method. The influences of the connection over the top of the structure’s lateral displacements, and acceleration and the bottom of the structure’s overall shear forces were discussed also. The conclusion of this paper may provide scientific basis to the structure design.