Abstract: In order to study the influences of controlled cutting strand length on the releases of tar and NNK in mainstream smoke of slim cigarettes, two slim cigarettes of a certain specification were prepared under different tobacco cutting modes using the same tobacco and auxiliary materials and keeping the other processing parameters and quality indexes the same. The cigarette samples made under the conventional cutting mode were marked as the control, and those made under the 40 mm cutting strand length as the test samples. The total releases and puff-by-puff releases of tar and NNK in mainstream smoke of the control and the test samples were compared. The results showed that: 1) the NNK release in mainstream cigarette smoke decreased by 17.07% with the 40 mm cutting strand length; 2) the variation ranges of puff-by-puff releases of tar and NNK of slim cigarette were also reduced; 3) the median value of maximum coal temperature in each puff of slim cigarette increased puff-by-puff; 4) the maximum coal temperature of the cigarette was mainly distributed in the fifth puff of the test samples, while the distribution of maximum coal temperature of the control was dispersed.