Abstract: In order to simulate the fact that the foundation soil is generally subjected to overlying loads and so on, a loadable osmosis apparatus is developed in this paper. The typical dilated mudstone at the second double line of the Lanxin railway is taken as the research object, and the permeability test under different load grades of the original and remolded soils is carried out. Value of the load is 0, 0.1, 0.2, 0.3 and 0.4 MPa. The results show that, the coefficient of permeability increases slightly with the increasing infiltration time. The coefficient of permeability of the undisturbed soil decreases with the increasing load. The results, provide a basis for analyzing the decrease in permeability of the foundation soil with the burial depth. The coefficient of permeability of the remolded soil decreases with the increasing load. For the high fill road foundation soil, the overburden load has an effect on the permeability. By further comparing the permeability of the intact soil and remolded soil, it is found that the coefficient of permeability of the remolded soil is 1 order of magnitude larger than that of the intact soil. The variation law of the coefficient of permeability is compared, and the reasons for the change in the permeability of the undisturbed soil and remolded soil are analyzed.