Abstract: The wetting tests of coarse-grained soil under the equal stress ratio path are performed using the basalt rockfill of Gushui concrete face rockfill dam. The tests results show that the wetting deformation of soil under equal stress ratio path is affected by stress state and loading stress path. The stress path is added in the traditional wetting deformation formula, and the volumetric stress and reference stress level are used to simulate the influences of stress state on the wetting deformation. A formula for the wetting deformation under equal stress ratio path is developed. The developed formula can accurately simulate the wetting deformation of the coarse-grained soil under equal stress ratio path.