In order to study the treatment scheme and parameters of the soft foundation on the back of the bridge abutment, a highway cross-river bridge project is taken as an example, the numerical simulation method is used to research the deformation law of the soil subgrade treated by "CFG pile + foam concrete", and the sedimentation influence parameters of the scheme are analyzed. The results show that: 1) The sedimentation value of the top surface of the subgrade treated with CFG pile with traditional filling is mainly increased within 20 m from the abutment, and the sedimentation value of the "CFG pile + foam concrete" scheme is mainly increased in the range of 15 m, and the maximum value is reduced by 3.4 cm; 2) The increase of CFG pile length, pile diameter and pile spacing, and the decrease of foam content of foam concrete are all conducive to the sedimentation control of the top surface of the subgrade; 3) The density of foam concrete can effectively reduce the load of the roadbed within a certain range, but with the increase of foam content, the settlement value will be gradually increased. In the actual project, appropriate parameters should be used to control the project cost while ensuring that the subgrade sedimentation is controlled. The results can provide references for the selection of treatment parameters for soft foundation at bridgehead.