Abstract: Similitude model test is very important in geotechnics research．But conventional gravity field of lg model test fails to reach the prototype stress leve1, because the stress-strain behavior of soil depends on its level of effective stress. Centrifugal model can provide high body force, so it is used widely in geotechnics, although it has some drawbacks. In this paper, a new model test of soil, the hydraulic gradient similitude (seepage force) model, is introduced through a pile’s seepage force model test. The seepage force model employs a high body forces, hence the high stress levers approaching field conditions can be reproduced. It overcomes some failing in conventional model and centrifugal model of geotechnics. So it is very useful in studying the piled foundation and other practice in geoteehnical engineering.