Abstract: An engineering design case about the 3rd Aodang cable-stayed bridge in Macao is investigated, using the finite element analysis program ANSYS. 3-D elements, element BEAM188, element BEAM4 and element SHELL63 are used in the dynamic FEM model. The dynamic characteristic is discussed under two different boundary conditions at the bottom of the bridge tower: The fixed end and the interaction of pile-soil. In addition, a linear seismic response analysis is performed by employing the response spectrum method and the time history analysis method, respectively. Based on two kind of mode combination methods and three group of mode numbers, the maximum seismic response of structure are carried out. The time history analysis is conducted for the cable-stayed bridge subjected to three earthquake ground motions in the longitudinal and transversal bridge direction, respectively. The internal force, displacement and the time history response of the main girder and the mid tower are obtained.