Abstract: The changes of amylase activity and starch content in flue-cured tobacco leaves during middle to late growing stage were studied in Pingdingshan, Henan Province.The results showed that:1) the amylase activity in the twelfth middle leaf increased gradually before budding stage and peaked in budding stage, then reduced gradually until rallied in early round top stage;the other peak was in mature stage, then dropped again;2) the accumulation of starch in leaves increased gradually along with growth and mature of the leaves.The peak of dry matter accumulation were in mature stage, and the peak of starch content in leaves were in ripe stage, both of them declined with the senescence of leaves.