Abstract: Duncan-Chang nonlinear model has been widely used in numerical analysis of stress-strain in engineering. Duncan-Chang model has K、n、Rf、c、 and other material parameters. These parameters of Duncan-Chang model are confirmed through analysis of triaxial test data in the Hangzhou Bay area. In the calculation process, it is found that the discreteness of some parameters is too large, so that the selection of parametersis more difficult, and the application of the model in engineering is also affected, the main reason is that the change of the value of Rf. We put forward a method, it is assumed that the value of Rf is a certain value, and then to obtain other parameters. This data processing method can not only simplify the model calculation, but also can improve the efficiency and accuracy of the model calculation.