According to the WHO recommended regulation for 9 priority toxicants in cigarette smoke, the collaborative study on specific analysis methods was achieved in 2014. The results of precision under reproducibility condition showed that the Reproducibility Relative Standard Deviation (RSDR) for tar, nicotine, CO in mainstream smoke were clearly lower than other Harmful chemicals. Comparing with the analysis precision results under two smoking regimens conditions, no significant difference of RSDR for Harmful chemicals was found between ISO and HCI smoking regimes. Besides, the RSDR and overall mean ( ) of Harmful chemicals in mainstream smoke accorded well with the Horwitz curve under ISO regime, but the RSDR did not have strong dependences on under HCI regime. Accord to ISO/TS 21748:2004 , the measuring uncertainty for 9 high priority toxicants level in µg per mg nicotine in cigarette smoke based on the reproducibility results were calculated. The results demonstrated that: Tar, nicotine and CO under ISO smoking regime were the most robust characterization in the tobacco mainstream smoke, and also good characters for product ranking. According to the requirements for assessment and reporting of compliance with specification, because measurement variability among 20 typical commercial samples was very little under HCI regime, the measuring uncertainty had an extremely great influence on judgment of compliance with celling of priority toxicant recommended by WHO TobReg.