Abstract: A rapid and accurate method for determining the deliveries of tobacco-specific N-nitrosamines, NNN, NNK, NAT and NAB, in mainstream cigarette smoke by gas chromatography-tandem mass spectrometry (GC-MS/MS) was established. The results indicated that:1) With ammonia as reactive gas and under the mode of positive chemical ionization, the established method featured strong resistance to matrix disturbance and good selectivity. 2) In the concentration range of 0.25-100 ng/mL, the linear correlation coefficients of the four TSNAs were higher than 0.999. The limits of detection ranged from 0.021 to 0.027 ng/cig and the recoveries were from 92% to 104% with the relative standard deviation (RSD) of less than 6.5%. 3) The measured values of TSNAs in mainstream smoke of reference cigarettes basically agreed with the results reported in the literature. This method is simple, accurate, reliable, and suitable for the routine determination of TSNAs in mainstream cigarette smoke.