Abstract: The double-deck concrete box girder is composed of two kinds of material, steel and concrete, and their working properties can be represented by a tie rod-compression rod model composed of steel and concrete. A new topology optimization method called "windowed progressive structure optimization algorithm" is introduced to establish the tie rod-compression rod model reflecting the working mechanism of the structure, which provides theoretical guidance for simplifying the opening design of the double-layer concrete box girder web. This paper introduces the optimal topology solution to establish the tie rod-compression rod model and how to complete the structural reinforcement design. The result shows that the topological optimal solution obtained by the windowed progressive structure optimization algorithm can better represent the internal stress state of the structure; and by the optimization method, the opening ratio of I-beam structure is increased by 5.5 times compared with the experimental design, the ultimate load is increased by 1.2 times, but the amount of steel is reduced by 30%.