Abstract: With the increasing of vehicle ownership, bridge overload occurs from time to time, and bridge reinforcement is particularly important. UHPC is widely used due to its high strength, toughness, durability, and ability to effectively improve structural load-bearing capacity and corrosion resistance. In this paper, taking Beiwazi Middle Bridge as an example, the bearing capacity of unreinforced and UHPC reinforced Bridges is compared, and the numerical simulation is carried out by finite element software. The results show that using UHPC for reasonable reinforcement can increase the section bearing capacity of small box girders by 30% -40%, thereby improving the overall bending capacity of the bridge.