Abstract: In order to accurately express mainstream cigarette smoke yields required by new national standard cigarette,(GB5606.5-2005),the normality of selected specimens was hypothetically tested with Kolmogorov-Smirnov,Lilliefors and Shapiro-Wilk methods,the mean value and its interval of normal population of tar,nicotine and CO contents in mainstream smoke of 4 brands of cigarettes were estimated respectively according to statistical estimation theory and quality control theory,and the method for accurately marking the mainstream smoke yields of tar,nicotine and CO was discussed.The results showed that the modification of mainstream smoke yields labeled on the packets of the mentioned cigarette brands is necessary for the purpose of delivering information about mainstream smoke exactly.