Abstract: In arid and semi-arid region, some engineering problems emerged due to the change of water content in soils. It is known that the behavior of unsaturated soil depends not only on the mineralogical composition, soil structure, and stress state, but also on soil suction. The relationships between water content and suction in the soil can be expressed as soil-water characteristic curves (SWCC). Based on the test on SWCC of an expansive soil, the result obtained by using osmotic techniques is compared with that by convenient method. The influence of the stress and suction histories on the SWCC is studied.