Abstract: With the best regression of two factors of temperature and relative humidity(RH), the experiment studied the regularity of average price and rate of first class of flue-cured tobacco in different yellowing environment. The result showed that the influence of temperature and RH on average price and rate of first class of flue-cured tobacco was similar, which showed a trend of parabola curve with temperature or RH increasing. The maximum value of average price occur at 38.0℃ and 87.0%, the maximum value of the rate of first class occur at 37.6℃ and 86.5%. The result also showed that when the temperature or RH was in the range of 37.5℃ to 38.0℃ or 85.0% to 88.0%, psychrometric difference was 1.5~2.0℃, the average price and rate of first class would exceed 10 yuan per kg and 40% respectively.