Abstract: In order to research the puff-by-puff release characteristics of NNK in mainstream cigarette smoke under diverse intensive smoking regime,we used RM20H smoking machine connected with puff-by-puff unit to trap it automatically in mainstream cigarette smoke,thus realizing quantitative analysis.On this basis,at different intensive smoking regime modes,domestic commercial mainstream cigarette smoke of NNK content was puff-by-puff trapped,measured and analyzed.According to NNK content of detection in cigarette smoke of a single port,we studied its puff-by-puff trends delivered by mathematical statistics.The results showed that,under ISO mode,the puff-by-puff was significantly increasing in linear trend.The NNK emission trends were polynomial changed puff-by-puff under Massachusetts mode,and after the first 11 port,the release was gradually decreased.However,in the mode of Health Canada,the NNK release trends was polynomial changed,and gradually decreased after the first release 9.The linear fit of the various intensive modes were very good.