The changes in palisade tissue thickness, leaf thickness, and their ratio in flue-cured tobacco green leaves during field were studied. Leaf samples were taken from different leaf positions and ages in Heilonjiang Province. The results indicated that palisade tissue thickness, leaf thickness, thickness ratio of palisade and leaf decreased with the increasing leaf positions. With the increasing days after transplanting, there was no distinct change pattern about thickness ratio of palisade and leaf. The difference in palisade tissue thickness in different leaf positions was significant. The days after transplanting were positive correlated with palisade tissue thickness and thickness rate of palisade and leaf. The significant positive correlation was observed between palisade tissue thickness and thickness ratio of palisade and leaf, and between palisade tissue thickness and leaf thickness.