Abstract: To explore its stability and deformation mechanism, an optimized consolidation treatment scheme of drainage plate and preloading drainage for the embankment on soft soil foundation is proposed based on an embankment project. Two groups of centrifugal model tests are carried out under three levels of preloading conditions. The stability of untreated and optimized embankments on soft soil foundation is compared and analyzed from the perspectives of foundation settlement, pore water pressure and foundation strength. The results show that a smaller post-construction settlement for the treated foundation is observed under the loading conditions of three levels of preloading, and the earth pressure reaches a stable state in a short time under over-gravity field. Meanwhile, the dissipation capacity of pore water pressure is higher. The plastic drainage board and surcharge preloading foundation treatment method for the old embankment on soft foundation can improve the consolidation efficiency and stability. The research results may provide guidance for the section design of embankment and the optimization of foundation treatment on soft soil foundation.