Abstract: This study was conducted, using the method of slices of paraffin wax, to investigate anatomical structures in leaves of flue-cured tobacco at three transplanting dates of Longjiang911 variety on May 1st, May 10th, and May 20th respectively. The comparison and analysis of the thickness of leaf, spongy and palisade parenchyma were used to investigate the correlations of transplanting date with maturity. The result showed that transplanting date influenced thickness of leaf, spongy and palisade parenchyma significantly. The thickness of leaf, spongy and palisade parenchyma and the intercellular space of mesophyll for the tobacco transplanted in May 1st were the biggest of all treatments. But for the tobacco transplanted in May 10th and May 20th, the thicknesses of bottom stalk tobacco were thicker than others, the thickness of leaf decreased by rise of the leaf position.