Abstract: Four humidity levels were applied to air-curing of burley tobaccoto for comparing the effect of curing environment on organic acid content in burley tobacco.The results showed that the highest content of total 20 organic acids was in the lowest humidity level,while with exception of citric acid,the highest content of rest organic acids was found in the middle level of humidity.The content of semi-volatile organic acids and aliphatic acids were decreased following the humidity level increased from low,middle and high to control as the highest humidity applied in air-curing.Some volatile organic acid were undetectable concomitant with the humidity increasing.The content of nonvolatile organic acids was detected the highest in middle humidity of air-curing but the content of citric acid was the lowest.In addition,the highest of malic acid content was found in low humidity curing.