The effects of different field water capacities(60%～100%, 60%～90%, 60%～80%, 60%～70%) on the growth, quality and physiological characteristics of lettuce were investigated. The results showed that the greatest shoot fresh and dry weight, leaf area and leaf number were obtained by 90% irrigation maxima treatment, soluble sugar, soluble protein of lettuce gradually increased with the decrease of irrigation maxima, the vitamin C contents of lettuce under 80% and 70% irrigation maxima were significantly higher than those of other treatments. The highest contents of MDA, SOD, CAT and Pro were obtained by 70% irrigation maximum treatment. The highest yield was obtained by 90% irrigation maximum treatment, whereas the best irrigation maximum was 80% for the growth and quality of lettuce.