Abstract: ObjectiveIn order to provide theoretical basis for optimization of curing process, dehydration characteris-tics of tobacco K326 upper leaves were studied during curing. MethodUpper leaves of tobacco K326 were used as test materials. Dehydration characteristics, morphological changes and correlation between the two during curing process were analyzed. ResultDuring curing, dehydration degrees of each part were as followed: blade>whole leaf>primary vein. Per-centage of blade moisture loss content to whole leaf moisture loss content went through a down-up-down variation, percentage of primary vein moisture loss content to whole leaf moisture loss content went through an up-down-up variation. Shrinkage rate of leaf area and circumference shrinkage rate of primary vein increased as curing temperature rose. There was signifi-cant linear positive correlation between dehydration degree of whole leaf and circumference shrinkage rate of primary vein, dehydration degree of primary vein and circumference shrinkage rate of primary vein(R2>0.9500, the same below), as well as dehydration degree of leaf and shrinkage rate of leaf area. ConclusionThe dehydration characteristics and morphological changes of different parts in tobacco K326 upper leaf are different during curing. Dehydration degree of tobacco leaf can be judged by morphological changes of primary vein, which can provide reference for optimization of state parameters of tobacco leaf in curing process.