Abstract This thesis focused on the investigation of structural behaviors of cable-stayed bridge and extradosed bridge with different heights of pylon and combinations of internal and external prestressed tendons. Single tower cable-stayed bridges with different heights have been designed and another extradosed bridge with the same geometric shape is studied to compare the structural behaviors and engineering benefits. In this thesis, we used TANGO as software to do the analysis and discuss the cable forces, the moment, axial force, shear forces, vertical displacement of the main deck with different loading combinations. Finally, the safety and benefits of two type of bridges are compared and hope it is helpful for the engineers in the future.