Abstract: A series of single-line wetting deformation tests are carried out on the gravelly soil core materials using a large stress triaxial apparatus to systematically investigate the variation of wetting deformation with stress level and confining pressure. According to the test results, the wetting deformation of the gravelly soil core materials is obviously related to the stress level and the confining pressure. Under of high confining pressure and stress level, the external force changes the saturation state of a specimen, and the gravel soil sample gradually transits from an unsaturated state to a nearly saturated one, indicating that a 'stress saturation' phenomenon exists in the gravelly soil materials, and resulting in less obvious wetting deformation during the wetting process. When the confining pressure is small, the wetting strain increases with the increasing stress level. When the confining pressure reaches a certain value, the wetting strain decreases with the increasing stress level, presenting an obvious bifurcation phenomenon, showing a more complex pattern. Finally, a wetting deformation model for gravel soil and its parameters are put forward, and can be used as the basis of wetting deformation analysis of high earth-rock dams.