Rock salt underground storage is an important way of energy reserves. The research of rock salt dissolution characteristics under triaxial stress provides theoretical basis for shape control，security building of rock salt underground storage in the process of making aqueous cavity. The dissolution characteristics of rock salt specimens experiment with triaxial testing machine under triaxial stress，through a lot of rock salt dissolution tests，finds that dissolution characteristics of rock salt change remarkably under stress. Analyzing the relationship between the stress of rock salt specimen with the water hole and sample external axial compression or confining pressure，equivalent stress is adopted to describe the stress distribution of the running water hole wall. Triaxial stress and dissolution coupling experiment on the different confining pressure is carried out to analysis the variation between rock salt dissolution rate and equivalent stress under different confining pressures. The results show that rock salt dissolution rate decreases first and then rapid increases with the increase of equivalent stress. The main impact of the stress for rock salt dissolution rate is that cracks development and corrosion area in rock salt specimen are changed because of the triaxial stress loading. Dissolution rate reduces as a result of corrosion area decreasing (crack closure) in the elastic stage，however dissolution rate increases because of corrosion area increasing (crack development) in the plastic stage.