Abstract: The changes in appareat feature of leaf, weight per-leaf and wight per-unit area of leaf during different maturing stage were studied.During flue-curing, the rates of water loss and chlorophyll degradation of leaves in different ages were analysed.Finally, the intrinsic quality and economic characters of flue-cured leaves were examined.The results indicated that it was optimal to harvest tobacco leaves at the ages of 9 weeks, 11 weeks and 10~12 weeks for lower, middle and upper part of stalk respectively.