The main building of this project is 99m × 79m with a height of 60m. The structure is composed of towers of 4 different rigidity. This paper investigates the system characteristics and the seismic performances of the structure. Under the actions of multiple earthquakes, the decomposition reaction analysis and elastic time history, analysis are used to carry out calculation and stability analys is of the whole structure. Some constructional measures were employed to enhance the seismic performances of weak components so as to ensure the seismic safety of the building. The results indicate that this structure system is safe and feasible.