Because of the increasing span of concrete cable-stayed bridge,  the construction simulation recently becomes more focusing on both the design and construction.  This paper introduces the optimization theory and method into the calculation of cantilever construction of girders. The example bridge is a long-span prestressed concrete cable-stayed bridge with a 370 m central span length under construction in China. Using spatial nonlinear FEM,  the actual cantilever construction process of concrete box-shaped girders is simulated,  the tensioning force of cables as well as the prearranged height of girders in construction state is obtained. At the same time, the influence of structural geometric nonlinear characteristics and physics nonlinear characteristics in the cable force optimum are investigated,  the measures to reduce the influence are put forward.