Weight of post-tensioning prestressing extradosed cable-stay bridge superstructure part formed from concrete, non-prestressing reinforcement, and prestressing reinforcement and stay cable tendon weight. Main load-carrying members, which are, girder, stayed-cable, and pylon are considered to apply structural optimization techniques in the superstructure component of the extradosed cable-stayed bridge. This research paper evaluated the optimum depth of the girder with pylon height, angle of stay cable, and effect of concrete grade in the three main parameters of an extradosed cable-stay bridge. Then identification of significant and insignificant design variables using sensitivity analysis by considering cable stiffness, girder weight, and stay cable tension. Structural optimization was carried out by taking the minimization of the total material weight of girders, pylon, and angle of stayed-cable as an objective function and all requirements of strength, stability, serviceability, and fatigue as constraint functions. As a case study Abay‘s extradosed cable-stayed bridge first design by China Communication Construction Company. It has two twin box girders with 24.7m width and a length of 380m. The width of the top of the box girder is 24.7m, and the width of the bottom plate gradually changes from 9m to the end fulcrum. The main tower adopts a double-column tower, the tower beam is consolidated. The tower root size is 4m x2m (lateral), and the tower top dimension is 3mx2m as respectively. The bridge is subject to five main load cases, dead, live, wind, settlement, and temperature loads. This paper gives an optimum cross-section of the superstructure main component of the Abay bridge by using the fixed load parameter that has already been defined by the designer company. Effects of girder depth, angle of cable-stayed, and pylon height with the effect of concrete grade on the optimum weight were investigated. The results of structural optimization indicate that optimum girder depth is 5.129m at pier level and 2.62m at span. The optimum pylon height was found to be 24.827m. And optimum stay cable length was reduced from conventional design output length by 10% from total values. Optimum design of pylon height reduced weight of conventional design by 20.03% and optimum design of box girder reduced girder weight by 19.47%. Paper gives the more reduced weight of bridge by 49.47% from conventional design output by using same material grade.