Abstract: The shape and height of the tower determine the height, the construction difficulty and the economical efficiency of the bridges. By using software MIDAS/Civil, this paper established spatial finite element model of whole bridge under the invariant cable and anchorage forms and the unchanged anchorage point distribution. The mechanical response of bridges with three tower shapes under the dead load and seismic load were analyzed, and it come to the conclusion that the diamond-type of tower is the optimal. Under the dead load of the finished bridge, the internal force and displacement of tower body, as well as the cable-force under the different tower heights of main girder were numerically analyzed. The least bending energy method is used to adjust cable tension in order to optimize the height of main tower, based on which, it is decided that the tower height of this bridge can be lower.