Abstract: The extradosed cable-stayed bridge has low towers and small number of cables. To investigate the dynamic behavior of the extradosed cable-stayed bridge, the paper established numerical model of Longjing Large-span curved bridge with varying design parameters. The two design parameters mainly considered herein were the design radius and the connection form between pier and beam. The influence of design parameters on the dynamic behaviors of the bridge were studied in this paper. Using the earthquake response spectrum data provided by National Seismic Code in 2008, the seismic behaviors of bridge models with different design parameters were investigated in the platform of Midas/civil. The results show that the two design parameters have a great influence on dynamic behaviors of extradosed cable-stayed curved bridges, especially on the overall seismic performance. This investigation can provide important reference for practical engineering and theoretical basis for seismic design of similar extradosed cable-stayed curved bridges.