Abstract: According to the analysis of the content of MDA and its variation in the leaves of the different flue-cured tobacco species in Nanxiong tobacco growing areas, the correlation difference between the maturity of tobacco leaves and the content of MDA revealed. The results showed that : 1) in vivo, the MDA content in upper leaves of ''K326'' showed "S" type change with time variation, and that of "Yueyan97" and "Yueyan98" showed exponential change with time variation, the content of MDA in the three species was 21.35, 18.75 and 20.59μmol/g at harvest time, respectively; The MDA content of the middle leaves in three flue-cured tobacco species all showed the same exponential change, and the MDA content was 19.74, 12.55, 12.98μmol/g at harvest time, respectively; 2) in vitro,the MDA content in upper leaves of "K326" showed exponential change with time variation, and ''Yueyan97'' and ''Yueyan98'' showed "S" type change; The MDA content in middle leaf in the three Flue-cured Tobacco species showed "S" type change; the vitro MDA content was reached to the level of harvest in a short period of time, and the content of MDA in the upper and middle leaves all showed "S" type change, when the harvest value was reached, it was just the turning point of the "S" type, which meant the change of vitro MDA content in tobacco leaves was consistent with the change of MDA content in vivo before the inflection point. The results showed that the content of MDA and the change rule of could be used to indicate the maturity (ripe, mature and over matured) of different Flue-cured tobacco.