To address the problem of selecting aggregate sources for Jinping-I dam restricted by environmental and economic factors, alkali-active aggregate had been used in the dam concrete by restraining the alkali-aggregate reaction of sandstone through measures of combined aggregate, high dosage of fly ash, and strict control of alkali content. This was the first time that alkali-active aggregate was adopted to an ultra-high concrete arch dam. Now that the dam has been in operation for about 10 years, it is necessary to scientifically evaluate the effectiveness of the long-term prevention of alkali-aggregate reaction of dam concrete. Researches on the preventive measures against alkali-aggregate activity during dam construction were briefly reviewed and summarized, and then the long-term effectiveness of such preventive measures was examined via petrographic analysis, microscopic morphology and product analysis, accelerated curing length measurement and elastic wave test on dam concrete core samples that have been in operation for 10 years. Test results revealed no harmful alkali-aggregate reaction inside with sound quality of the concrete core sample, which verifies the long-term safety and effectiveness of the alkali-aggregate preventive measures adopted in the dam concrete of Jinping-I Hydropower Station.