Abstract: A field experiment on Yunyan 87 and K326 was conducted to study the effects of nighttime insulation on the contents of plastid pigments, polyphenols, non-volatile organic acids and volatile aroma components in flue-cured tobacco in the high-altitude areas in Yunnan. The results showed that: Comparing with the control groups, 1) The contents of lutein and β-carotene in the treated tobacco increased extremely significantly, particularly in lower leaves of K326 and upper leaves of Yunyan 87; the content of malic acid also extremely significantly increased, notably in upper leaves; while the content of citric acid extremely significantly decreased, it decreased the most in lower leaves. 2) The content of chlorogenic acid significantly increased in the upper leaves of K326, while significantly decreased in the upper leaves of Yunyan 87. 3) The contents of neophytadiene in all samples (except for the lower leaves of K326) extremely significantly increased, and the total amounts of aroma substances (excluding neophytadiene) increased more significantly in the middle leaves of K326 and the upper leaves of Yunyan 87. Nighttime insulation was a favorable measure for improving aroma quality of tobacco in the high-altitude areas in Yunnan, notably the middle leaves of K326 and the upper leaves of Yunyan 87.