Abstract: Abstract: For defining the relationship between the different mature period and leaf tissue structure，Explored the appropriate intaked time. Using the method of slides observation under microscope, this study was conduced to investigate the anatomical structure of the maturation period and delayed period from upper and middle positions of tobacco K326 and Yunyan 87. The results showed that: with the period of intaked was delayed, thickness of palisade tissue and spongy tissue, the thickness ratio of palisade to spongy, and other anatomical parameters were downtrended, gap of mesophyll cells were increased, tissue cells gradually disassembled; the thickness of leaf and palisade tissue, and other anatomical parameters were varied with the different period of maturation, in the same period, with the rising of the stalk positions, the leaf thickness, the palisade tissue thickness were decreased; the intaked period of tobacco K326 longer than Yunyan 87. From the dissecting features closely related to tobacco quality, it seemed that the appropriate intaked time of tobacco K326, the upper position not beyond 14 days, the middle position not beyond 21 days; Yunyan 87, the upper position not beyond 7 days, the middle position not beyond 14 days.