Abstract: In order to identify possible causes behind the differences of sugar contents between cured tobacco leaves from Henan and Yunnan, starch degradation-related genes were identified on the basis of gene array data of middle tobacco leaves grown in Xuchang and Yuxi at mature stage. The gene array results were verified by qPCR and enzyme activity, and the contents of starch and total sugar were detected. The results showed that there were four starch degradation-related genes:two α-amylase genes and two β-amylase genes. The expressions of four amylase genes and the activities of α-and β-amylases were higher in Yuxi leaves than in Xuchang leaves. The starch contents in middle tobacco leaves from Yuxi and Xuchang at mature stage were 33.00% and 35.00%, respectively. And there was no obvious difference of starch content between Yuxi and Xuchang leaves. The total sugar content in Yuxi tobacco leaves (2.10%) before flue-curing was lower than that in Xuchang (3.20%). However, the total sugar content in cured Yuxi leaves (36.46%) was higher than that in cured Xuchang leaves (20.60%). The results indicated that amylase was a key influencing factor of the total sugar content in cured leaves, while the starch accumulation in tobacco leaves before flue-curing was not.