Abstract: With the best regression of two factors of temperature and time, the experiment studied the relationship between leaf quality and change-less temperature and time in the stem-dring stage of flue-cured tobacco. The result indicated that the content of petroleum ether extract, aroma and taste of cured-leaf presented a trend of parabola curve, which increased to a higher level in the range from 54.3 to 57.0 degrees of temperature and 12.5 to 15.5 hours of the time to the aroma and taste score and 54.3 to 56.3 degrees of temperature and 5 to 12.5 hours of the time to the content of petroleum ether extract. The study also showed that it had a good relationship between the content of petroleum ether extract and aroma and taste.