Taking an embankment widening project as an example, the feasibility of self-compacting cement soil as the filling material of a new embankment was discussed in this paper. Based on the lab test data of excavated soil, numerical investigations on the settlement and differential settlement of the new and old embankments were carried out using the software Plaxis2D, and the stability of embankment slope was also analyzed. The influence of the new embankment slope ratio and geogrid laying was considered in the analysis. The results indicate that as the filling material of a new embankment, the self-compacting cement soil can effectively control the settlement and differential settlement, and laying geogrid can reduce differential settlement of the new and old embankments and significantly improve the stability of the embankment, the self-compacting cement soil is applicable in the embankment widening project.