Abstract: The soil-water characteristic curve(SWCC) is an important constitutive feature of unsaturated soils.Meanwhile it is also an indispensable requirement in hydraulic transport modelling and soil mechanics analysis.In this paper,at first,a review of the development in SWCC modeling was given,then the soil-water characteristics was explained according to the physical and chemical behaviours of the phases involved in unsaturated porous media.Using the traditional capillary theory,the volume averaging theorem and the advanced interfacial surface theory,a formula representing the soil-water characteristics of unsaturated porous media was derived.In this formula the internal linkage of the SWCC to the specific surface area of soil porosities was demonstrated,and agreed with the experimental observations mathematically.Based on this formula,a fitting model was proposed for the SWCC.Finally,this model was tested to fit the SWCC measurements of a wide range of porous materials,and compared with other main models.