Abstract:Rock salt is known for its very low permeability. Therefore,rock salt formations are commonly used as host rock for storage caverns(oil or natural gas) and are being considered for the long-term disposal of radioactive waste. The technology of construction of underground repository for energy in rock salt is rather mature in industrialized countries,but in China it is just ongoing now. The mechanical properties and stability of salt caverns have been paid extensive attention by domestic researchers. However,study on permeability of rock salt is seldom seen because of the precision limit of testing equipments. In order to investigate the permeability of rock salt systematically,various viewpoints from a number of researchers have been taken into consideration. The relation between permeability and porous structure,porosity,Klinkenberg effect,capillary pressure is discussed in detail. It¢s concluded that the porous structure will take main responsibility for the extremely low permeability of rock salt. Fluid migration is affected by Klinkenberg effect and the extremely high capillary pressure,which are resulted from very small porosities in rock salt. Excavation in rock salt will destroy the initial state of equilibrium and lead to dilatancy deformation,which reveals the generation and propagation of cracks and increase of damage. Dilatancy and damage destroy the porous structure of rock salt and its permeability increases remarkably.