To analyze the seepage problem of groundwater during the development of potash salt mining area in Dongtai, Laos, a geotechnical seepage-erosion-stress coupling experimental device was used to study the permeability evolution of the rock salt collected from the mining area under pressure-dissolution coupling effect. The experimental results indicate that the average seepage velocity of the rock salt samples decreases first and then increases with the increase of hydraulic gradient during the experiment. The permeability coefficient of the rock salt samples decreases rapidly with the increase of hydraulic gradient at first, then increases slowly and finally tends to be stable. The permeability evolution of the rock salt is affected by both dissolution and confining pressure. The dissolution promotes the formation of seepage channels and enhances the permeability of the rock salt sample. The confining pressure makes the seepage channel close and reduces the permeability of the rock salt sample. It is a process of mutual promotion and mutual inhibition. Dissolution can promote the development of inhomogeneous concentrated seepage channels interior of the rock salt specimen, profoundly affecting the permeability evolution of the rock salt.