Abstract: In order to investigate the influences of breakable capsules on the physical properties of filter rod and cigarette, mainstream smoke chemistry, the differences of physical properties between filters and cigarettes with/without breakable capsules and the variations of routine indexes of mainstream cigarette smoke were analyzed. In addition, the physical properties and mainstream smoke indexes were tested before and after crushing capsules. The results showed that:1) Comparing with the filter rods without capsules, the standard deviation (SD) of pressure drop of filter rod with capsules increased by 39 Pa at the same tow filling volume and by 17 Pa at the same pressure drop. The roundness of filter rods with capsules decreased by 0.039 percentage points at the same tow filling volume and by 0.079 percentage points at the same pressure drop. 2) At an equal net cut tobacco content, the stability of weight and draw resistance of cigarettes with capsules became worse, the release of nicotine in mainstream smoke with capsules was reduced by 0.04 mg/cig comparing with the cigarette without capsules at the same tow filling volume of filter rod, while the levels of tar and carbon monoxide in mainstream smoke with capsules raised by 0.2 mg/cig comparing with the cigarette without capsules at the same pressure drop of filter rod. 3) After crushing capsules, the draw resistance of cigarette was reduced and the stability of draw resistance became worse. The releases of total particulate matter, tar, nicotine and carbon monoxide in mainstream smoke increased by 1.31, 1.20, 0.06 and 0.40 mg/cig, respectively. 4) Before crushing capsules, the consistency of mainstream smoke indexes between cigarettes with/without capsules could be ensured by keeping the net cut tobacco content and draw resistance of cigarettes consistent. After crushing capsules, the pressure drop of filter rod with capsules should be 376 Pa higher than that of filter rod without capsules to ensure the consistency of mainstream smoke indexes.