Abstract: For better design of filter rods with breakable capsules, filter rods with breakable capsules of different diameters and different positions were prepared and assembled into cigarette samples. The effects of filter rod design parameters on the major physical indexes, routine mainstream smoke indexes and nicotine filtration efficiency were investigated. The results showed that: 1) With the increase of capsule diameter, the filter ventilation rate and draw resistance of cigarettes increased by 28.4% and 28.1% respectively; the releases of tar and nicotine decreased by 6.8% and 3.3% respectively; and the nicotine filtration efficiency raised by 15.8%. 2) With the increase of the capsule distance to mouth end, ventilation rate and nicotine filtration efficiency were the lowest at the shortest distance between the capsule position and ventilation hole position. 3) Post capsule crushing, cigarette draw resistance significantly decreased by 210 Pa, the maximum increases of tar and nicotine releases reached 1.9 and 0.08 mg/cigarette respectively, and nicotine filtration efficiency decreased by 16.3%. 4) Post capsule crushing, filter ventilation rate and total ventilation rate reduced generally, cigarette draw resistance increased, and nicotine and tar releases raised gradually with the increase of capsule diameter. 5) Post capsule crushing, nicotine and tar releases increased gradually and nicotine filtration efficiency decreased gradually with the increase of the distance between the capsule position and mouth end. The maximum nicotine and tar releases and the minimum nicotine filtration efficiency appeared at the shortest distance between the capsule position and ventilation hole position.