Abstract: An analytical method to determine volatile benzene in cigarette packing was presented by headspace gas chromatography mass spectrometry (HS-GC/MS), and the method for the uncertainty measurement was evaluated. The mathematical model of measurement was set up. The different parts of uncertainty were analyzed. The combined standard uncertainty was calculated, and the evaluation of the uncertainty of this analytical method was observed. The results indicate that the uncertainty of the repeatability is the largest factor contributed to the combined uncertainty．The next is caused by the benzene content calculation using the standard curves, and the uncertainty of preparing the standard solution is low. In addition, the recovery values of this method with 100% is not significant by statistic analysis. When the content of benzene residue is 0.010 mg•m^-2，the expanded uncertainty is 0.001 mg•m^-2(k=2).