The enclosed condition of caprocks is one of the key factors in exploring hydrocarbon source in the sedimentary carbonate beds in South China.The paper summarizes our recent work in water-rock interaction of caprocks around the upheaval in the middle of Yunnan province.The experiment simulated dissolution and mass loss of main ions of clay and carbonates caprocks in rain water and brine under different temperatures.By measuring major ions and mass loss,it was found that the water-rock interaction is very important in caprock preservation and breakage.The solubility and content of ions in caprocks varies in various waters and flow states,with clear dissimilarity between clay and carbonate rocks.In rain water,the concentration of both cation and anion in mud rock decreased until tranquilization,and the trend are different between mud and carbonate rocks.In a brine environment,the dissolution is restrained with the complex transformation of ion concentration,and becomes stable with time,and there is a little different between the two kinds of rocks.And the changes become complicated with higher temperature.The loss amount of caprocks was huge because of the exposure and chemical erosion during the Caledonian tectonic movements around the upheaval in the middle of Yunnan province.