The dissoluble erosion of concrete affects the stability and safety of dams seriously. In this research, concrete’s dissoluble erosion of 35 dams in Jiangxi province was analyzed systematically by means of field survey, water and precipitate sampling and analyzing. Results show that the large and medium-sized dams in Jiangxi Province suffered from erosion of different levels, and the ambient water with low concentration of HCO₃^2- is an important factor which leads to the corrosion of concrete. When dams are exposed to water of low HCO₃^2- concentration, the composition, mix proportion, construction quality and curing time of concrete play critical roles in preventing the dam from dissoluble erosion. Though the dams have been reinforced in recent years, some of them are still suffering from severe dissoluble erosion. Therefore, in-depth and systematical researches are necessary on the dynamic migration of Ca²⁺, the microcosmic mechanism of dissolution and the way of inhibiting the erosion.