Abstract: To clarify the rules behind accumulation and variation of tobacco specific nitrosamines (TSNAs) in cigar tobacco leaves at mature, air-curing and fermentation stages, the middle and upper leaves of cv. Dexue 3 (cigar wrapper) and cv. Shiyan 1 (cigar filler) were sampled at the above three stages and their TSNA mass fractions were determined. The results showed that the TSNA accumulations of Dexue 3 at the three stages were between 153.53-208.26, 574.10-597.50 and 647.40-1 090.73 ng/g respectively. The total TSNA accumulations of Shiyan 1 at the three stages were between 305.63-526.81, 1 700.45-2 494.93 and 1 529.60-2 373.37 ng/g respectively. The accumulations of each TSNA and total TSNAs in the leaves at the different stages differed slightly between the two cultivars, the accumulations were all less before maturity and more at air-curing and fermentation stages. The total TSNA accumulation ratio of Dexue 3 was 30.65%-42.73% at air-curing stage and 46.29%-58.23% at fermentation stage and that of Shiyan 1 was 45.26%-48.22% and 40.71%-45.87% respectively. With the proceeding of air-curing and fermentation processes, the total TSNA contents in the leaves increased gradually. Therefore, air-curing and fermentation are the important stages for TSNA accumulation and the key stages for controlling their accumulation.