A three-dimensional soil-water characteristic surface model considering deformation is established to study the effect of deformation on the soil-water characteristics and the hysteresis effect of unsaturated loess. It is established by first constructing a relationship between water content and pore ratio under constant suction conditions

and then introducing the effect of suction. The model can describe the change of water content with pore ratio and suction during wetting or drying of loess with different initial pore ratios. Wetting and drying tests on loess show that the water content under constant suction conditions is linearly related to the pore ratio

which verified the theoretical assumptions of the model. Additionally

soil-water characteristics of equal pore ratio state can be determined from the model

and by comparing them with the experimental results

it is found that the deformation caused by suction in the drying path has a greater influence on soil-water characteristics

which will reduce the characteristic parameters and suppress the hysteresis effect.