In the field of road engineering, expansion joints serve as crucial structural details, with their stability and durability playing a vital role in the safety and lifespan of the entire road. As material science continues to advance, one-component polyurethane sealant, as a new type of road repair material, is gradually showcasing its unique advantages in the protection of road expansion joints. This article will explore the protective effects of one-component polyurethane sealant on road expansion joints from multiple aspects.