With the best regression of two factors of temperature and relative humidity, the experiment studied the relationship between leaf quality and curing environment in the yellowing 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 37 to 38 degrees of temperature and 84 to 90 percent of relative humidity (RH). The study also showed that it had a good relationship between the content of petroleum ether extract and aroma and taste.