Abstract: Phosphogypsum can be corrosioned directly by the water. The special crystal shape and impurity of phosphogypsum also affect its dissolution feature, which brings phosphogypsum karst phenomena. The influence of compound karst of the phosphogypsum pilling up the carbonate rocks area will bring hydrology, engineering geology questions. The phosphogypsum Karst is a special question that affects the stability of stack, dam and ground water environment. Some engineering treatment countmeasures about enhancing stability of phosphogypsum dam, prevent leakage of stack and protect the ground water environment be gived.