Abstract: Based on the Boussinesq solution of elastic semi-infinite ground, the stress solution of ground is obtained, and the calculation formula of ground settlement is expressed by the stress solution. As for some given q-s curves, the back analysis is used to analyze parameters of Duncan-Chang model based on the least square method. It is proven that the present method is accurate and practicable, and the parameters obtained by back analysis agree well with the results of settlement experiment.