Abstract: By analysis on the seepage performance at foundation of some dams which have been in operation for more than 30 years, conclusion was gotten that most dams were of good seepage control effect, seepage reduced as time passing and the requirement of standards on uplift pressure could be met. Some factors would exert adverse influence on seepage control and its durability, such as no proper seepage control measures designed, no intact curtain, defects caused by foundation excavation, grouting disturbed by underground flowing water and et al. Further, some advices were presented, including periodic analysis on the foundation sludge, research on sulfate erosion and timely dredging of drainage holes and reinforcement grouting.