Abstract: In order to increase climatic resource utilization efficiency and solve the issues with maturity and leaf quality at late growth stage of flue-cured tobacco, effect of effective accumulated temperature on leaf age and maturity was investigated. The results showed that the effective accumulated temperature requirement for leaf mature of same leaf position varied little with transplanting time. The effective accumulated temperature was 570-590 ℃, 850-880 ℃, 1280-1310 ℃ for the 4th leaf, the 10th leaf, and the16th leaf, respectively. Therefore, it is possible to predict the time of leaf mature by calculating the amount of effective accumulated temperature, thus plant the tobacco on optimum time and improve leaf maturity and quality.