There are many defects of the main soil swelling pressure measuring methods at present. So

an improved method is put forward which could measure the soil swelling pressure under approximately completely restricted swelling conditions. Taking compacted laterite as study object

the swelling pressures of specimens have been measured at different initial water contents and dry densities. Comparing with the test results which belong to swell-consolidation method

it is indicated that the former swelling pressure values are less than the later ones. Meanwhile

the restricted swelling method has three major advantages. Firstly

it accords well with the definition of swelling pressure owning to the soil un-deformation after soaking. Secondly

it takes less time and occupies smaller space. Thirdly

it can measure swelling pressure within wide range of water content. Furthermore

the samples mesoscopic pore size distribution features under different conditions have been measured by mercury intrusion method and nitrogen adsorption method. The results show that the influence of sample water content is significant on the pore distribution of compacted laterite at the same dry density. The compacted laterite occurs “irreversible” swelling due to the incursion of water molecule into laterite crystal and grain. The “irreversible” swelling degree of laterite is major reason which brings to difference swelling pressure values between the restricted swelling method and swell-consolidation method.