Abstract: Comparative study the yield of tar, nicotine, water, carbon monoxide, ammonia and phenol in mainstream smoke of different cigarettes under two smoking methods, ISO method and Health Canada method. The yield of tar, nicotine, water, carbon monoxide, ammonia and phenol in mainstream smoke under Health Canada method is the higher than them under ISO method. With the increase of filter ventilation rate, the increasing amplitude of the tar, nicotine, water, carbon monoxide, ammonia and phenol in the mainstream smoke is increasing under Health Canada method. It is found that the rates of increase of water in mainstream smoke under Health Canada method are greater than the other five components.