Abstract: In order to clarify the effects of different nitrogen amount and the ratio of nitrogen to potassium on the content of aroma substances in flue-cured tobacco KRK26, the field experiments were conducted to detect the content of aroma substances in tobacco leaves. The results showed that: (1) The 34 kinds of neutral aroma substances were detected of KRK26 tobacco leaves. The contents of benzyl alcohol, phenylethyl alcohol, cembratriene diol A, farnesylacetone and cembratriene diol D were relatively high, and the average values were 10.91, 7.75, 8.49, 6.59 and 5.17 μg/g, respectively. These aroma components played an important role in the fragrance, sweet floral and nutty aroma of tobacco leaves. The contents of other 29 aroma components were lower than 5 μg/g. (2) There was no significant difference in the content of phenylalanine, browning reaction products, cembranoid degradation products and neophytadiene among different nitrogen fertilizer and nitrogen-potassium ratio treatments, but there was significant difference in carotenoid degradation products, which were higher in A2B2 treatment. (3) The contents of megastigmatrienone C and D, β-dihydrodamascenone, 4-oxoisophorone, farnesylacetone, phenylalanine alcohol and formaldehyde, and the contents of pyridine, sugar alcohol and 4-cyclopentene-1,3-dione in browning reaction products in carotenoid degradation products were significantly different, which were significantly higher in A₁B₁ and A₂B₂ treatments. Therefore, we should pay attention to the application of nitrogen fertilizer in the production, and coordinate the ratio of nitrogen and potassium to further improve the quality of tobacco leaves. At the same time, it is recommended that the appropriate amount of nitrogen fertilizer for Dali KRK26 flue-cured tobacco is 75 kg/hm², and the ratio of nitrogen to potassium is not less than 1∶3.5.