Abstract: The maturing process was different between K326 and HD, and the maturity was different in breeds. While maturity thickness of leaf, length of palisade cells increased gradually, then declined, spacing of leaf increased gradually. So the structure of ripe leaf loosened properly, and it made for tobacco quality. The structure of stoma stabilized, but function fall during maturing, and the number of chloroplast in guard cell drooped, and it might be a symbol for maturing.