Abstract: Dynamic motel test has been widely applied to the study of soil-structure interaction, in which the preparation of model soil matters the most. This paper prepares samples with foil sampler of different dry densities and water contents according to the soil physical properties, and then subjects the samples to direct shear test to get the original shear modulus. Considering the results, the correlation between the original shear modulus and the soil dry density and water content is analyzed. The request of the preparation of model soil is obtained on the basis of similitude law in dynamic model test. The preparation of model soil without other materials is analyzed through with above findings. Then a qualitative way of the preparation of model soil is obtained. It can provide useful and helpful directions for the preparation of model soil in similar test.