Although there is currently a lot of research on saline soil, it is mainly focused on project survey, design, and construction period. There is still relatively little research on the variation of salt content over time in embankments filled with saline soil at home and abroad. In order to explore the variation of salt content in saline soil roadbed fillers over time and provide theoretical support for the design of saline soil roadbed in the renovation project, this article relies on the existing railway speed-up renovation project from Rohri to Multan in Pakistan. Through on-site investigation and a large number of on-site tests, the salt content in the existing roadbed fillers and the undisturbed soil on both sides is compared and analyzed, and the variation law of saline soil roadbed is summarized. For embankments filled with saline soil, the salt content in the roadbed filling gradually decreases over time and transitions to non saline soil. When using saline soil to fill the newly built roadbed, engineering measures such as widening the roadbed surface and slowing down the slope rate of the embankment should be taken. At the same time, priority should be given to construction. After soaking, the salt content in the roadbed filling can be effectively reduced. Directly using saline soil to fill the roadbed not only saves engineering investment but also ensures the safety and stability of the roadbed.