Abstract: In order to examine the effects of vacuum conditioning on tobacco leaf quality, the reduplicative test and comparative analysis of 9 kinds of representative flavorful tobacco leaves from high, middle and low grades were carried out with or without going through vacuum conditioning.The results showed that: comparing with leaves without vacuum conditioning, the vacuum conditioned leaves produced less breakages, possessed lower total sugar, reducing sugar, total alkaloid contents and lower sugar/alkaloid ratio, while total nitrogen, potassium and chlorine changed little;for the leaves of middle and low grades, the quantity and quality of flavor were affected scarcely, and the offensive taste and irritation were reduced effectively;for the leaves of high grade, though the quantity of flavor and smoke concentration somewhat reduced, the offensive taste and irritation reduced more perceivably.