Abstract: To study the effects of temperature on the quality and taste style of tobacco leaves at mature stage, a pot experiment using flue-cured cv. K326 (Nicotiana tabacum) was carried out. After topping, tobacco plants were transferred into artificial climate chambers with daily average temperature of 28.1 ℃ and 22.8 ℃ , respectively. Cell structure, pigment accumulation and aroma components in middle leaves were analyzed after growing for 30 days. The leaf ultrastructure analysis indicated that under the higher temperature treatment (28.1 ℃) at mature stage, the cell nucleus in leaves degraded more completely, the content of starch grain was more abundant, the number and volume of osmiophilic particles increased, chloroplasts fully degraded and thylakoid lamellae partially completed. LC/MS analysis showed that the contents of plastid pigments, including β-carotene, neoxanthin, violaxanthin, lutein, chlorophyll a and chlorophyll b, under the higher temperature treatment were lower than those under the lower temperature treatment. However, the contents of carotenoids degradation products (including linalool, isophorone, β-damascone, dihydroactinidiolide, megastigmatrienone-4, farnesylacetone, solavetivone) and chlorophyll degradation product (neophytadiene) in leaves under the higher temperature treatment were significantly higher than those under the lower temperature treatment. In conclusion, the higher temperature at mature stage promotes the degradation of cell structure and plastid pigment and the accumulation of cell inclusion, which is beneficial to the generation of aroma substances and greatly improves the quality and taste style of tobacco leaves.