In order to solve the problem of uneven settlement of the soft soil foundation， and to make the foam lightweight soil more widely used in embankment filling， the model in ANSYS finite element software is established， which can help the theoretical analysis of the embankment with different heights， density and elastic modulus of foamed light soil.Re-sults show that the elastic modulus of soft soil layer have the most effect on the settlement of subgrade， and the change of cohesion has little influence on the settlement of subgrade.Compared with the common subgrade， the foam lightweight soil roadbed can largely reduce the subgrade settlement.The increase settlement of the embankment influence by the in-crease of the height of the embankment， the decrease of the elastic modulus and the increase of the density.Meanwhile， it is found that the roadbed is prone to be unstable when the density of the foamed lights oilisover11kg/m³， and the height of the embankment is over or equal to 12m.