Abstract: In order to find out the suitable cut tobacco structure for making slim cigarettes, the relationships of cut tobacco's width, its length and proportion in tobacco blend with the density, physical indexes and mainstream smoke analytes of slim cigarettes were analyzed. The results showed that:1) The density of dense segment(5-9 mm longitudinally from tobacco end) of tobacco rod and compression ratio, the density ratio between the dense segment and normal segment (17-52 mm longitudinally from tobacco end), negatively correlated to cut tobacco length, and the standard deviation of rod density positively correlated to cut tobacco length. Cut tobacco length negatively correlated with the draw resistance, hardness, filter ventilation rate, dust content and loss of tobacco from the ends of cigarette, and extremely positively correlated to TPM, tar, CO and moisture contents. 2) In the case of 0.85 mm cut tobacco width, the density, physical indexes and mainstream smoke analytes of slim cigarette presented good controllability, the moisture content was high and stable, which is beneficial to moisture retention. When the proportion of cut tobacco longer than 6.80 mm was 4.0%, slim cigarette featured higher compression ratio, lower hardness and draw resistance, higher filter ventilation rate, stable indexes, relatively lower tar and CO and moderate nicotine contents in mainstream smoke. 3) Cut tobacco length directly influenced the axial density of tobacco rod, and then indirectly affected the physical indexes and mainstream smoke analytes of slim cigarette accordingly. 4) Through the control of proportions of cut tobacco longer than 6.80 mm and shorter than 2.29 mm, as well as fibrous processing of tobacco stem, broken strand increased by about 0.4 percentage point, cigarette rejection rate decreased by about 1 percentage point, the consistency of draw resistance promoted, hardness rose slightly, and the efficiency of slim cigarette maker improved to a certain extent.