Abstract: Embarking from the structural character of soft soil,this paper studied on the high void ratio,strong permeability and the compression curve of soft soil to discussed the settlement's calculation method in express way foundation. The back analysis method already became one effective way to forecast the later settlement. This method is to analysis and carries on the feedback to the engineering from room and time. It is a dynamic process. It not only includes various static state analysis carried on in normal regulations design period, but also includes the construction process, and according to the real settlement or other information carries on a series of feedback processing. It connects the design and construction closely. For estimating the later settlement,this paper analyzed the model parameters,and forecast the settlement curves. This paper also compares the real curves with the theory curves and forecast curves to evaluate the treatment methods.