Abstract: There are several important aspects, such as the formation cause of foundation sludge, effect of seepage calcareous segregation of dam body, the change trend of leakage quantity of dam foundation and the jeopardy of the cracks, related with the strength, stability and duration of the concrete dams. Combined with the project cases, this paper discusses their analytical methods, evaluation basis and jeopardizing degree, and gained some quantitative and qualitative concusions.?