Abstract: To effectively control the differential settlement of new and old embankments in highway widening projects on soft soil foundation, this paper adopts a geotechnical centrifugal model test to systematically study the deformation characteristics of the embankments under different reinforcement methods and combinations of embankment fill materials. Through the design of three different approaches, a comparative analysis is conducted on the effectiveness of geogrids and geocells in controlling vertical settlement and horizontal displacement, and the settlement control performance of two fill materials-graded gravels and weathered mudstones-are evaluated. The results show that under the condition of equal tensile strength and layout spacing of reinforcement materials, geogrids have more advantages in controlling vertical settlement, while geocells are more effective in restricting lateral displacement. Lightweight and high-strength graded gravels can effectively reduce the total settlement. The comprehensive differential settlement control design method proposed in this paper demonstrates excellent reliability and practicality, providing theoretical basis and practical guidance for similar projects.