Abstract: To study the effects of irrigation stage on yield and anthocyanidin content of purple potato in hilly area of central Sichuan basin under the condition of once irrigation, purple potato variety‘Rongziyu 5’was used as test material and five irrigation stage treatments such as non-irrigation, seedling stage irrigation, bud stage irrigation, flowering stage irrigation and harvest stage irrigation were set in this experiment. The results showed that: compare with non-irrigation treatment, irrigation treatment increased the leaf area index (LAI), dry matter accumulation amount, tuber dry weight and fresh tuber yield. Among them, the yield of bud stage irrigation treatment was 22.68% to 37.50% higher than that of control while the yield of flower stage irrigation treatment was 26.82% to 38.79% higher than that of control. In the tuber classification of flower stage irrigation treatment, the percentage of less than 30 g was lower while the percentage of more than 75 g was higher. The anthocyanidin content of potato tuber showed a tendency of decrease first and then increase with the development of crop growth. The anthocyanidin content of seedling stage irrigation treatment was the highest in different years. Therefore, under the condition of once irrigation, bud stage irrigation or flowering stage irrigation could obtain higher fresh tuber yield while seedling stage irrigation could obtain higher tuber anthocyanidin content.