In order to obtain the optimal parameters of temporary pier spacing, guide beam length and stiffness in launching construction of long-span bridges, optimize the internal force alignment of main girder and save material cost, an optimization method of main girder alignment and material cost based on non-dominated sorting genetic algorithm Ⅱ(NSGA-Ⅱ) genetic algorithm was proposed. Taking the maximum reaction force of the temporary pier and the maximum stress of the main beam section as the constraint conditions, a multi-objective optimization model of the temporary pier spacing, the length and stiffness of the guide beam and the alignment and material cost of the jacking in place main beam was established. The NSGA-Ⅱ genetic algorithm was used to iteratively solve the bar system model of the whole process of ANSYS launching construction, and the joint simulation optimization was carried out. The Pareto front optimization solution set was obtained by fast non-dominated sorting and elite retention strategy. Finally, the best solution was selected by technique for order preference by similarity to an ideal solution(TOPSIS). Through specific engineering analysis, the Pareto optimal solution set obtained has good convergence, and the design parameters can be selected according to different objectives. Finally, it is recommended that the temporary pier spacing is 59 m, the length of the guide beam is 35 m, and the stiffness of the guide beam is 0.15 times that of the main beam, which can provide reference for the design of related engineering construction schemes.