With the expansion of urban scale, the existing urban interchange bridges often have insufficient traffic capacity. In order to alleviate the increasing traffic pressure, more and more interchange widening bridges have been implemented, but there are many limitations for the design and construction. Taking an interchange reconstruction project in Zhengzhou as an example, the principles and ideas of bridge design are summarized. The limitations and design schemes of the project are expounded in detail. Various methods for controlling the deflection of the widening bridge are proposed. The finite element software Midas Civil is used to simulate the bridge schemes in order to further compare and analyze the rationality and feasibility of various methods for improving the stiffness of steel box beams. Finally, the most reasonable structural scheme is obtained, which has certain reference significance for the design of similar urban interchange widening bridge projects.