Abstract: This paper provides a detailed analysis of the history and technological evolution of the Bailey Bridge. Originally invented for military engineering units during early World War II， the Bailey Bridge is renowned for its simple structure， rapid deployment and erection， and excellent modularity. Since its inception in 1942， the bridge has played a crucial role in various battlefields and has seen extensive applications and technological advancements post-WWII. The paper delves into the technical evolution including truss combination， transoms， and deck systems， accompanied by design parameters at each stage. With continuous improvements and upgrades， the Bailey Bridge has expanded from military usage to civilian applications， standing as a pivotal technology in modern bridge engineering. Bailey bridges are often employed to replace bridges damaged by earthquakes， floods， or hurricanes， and act as temporary structures during construction.