In order to find out the function of combustion improver in reducing cigarette’s hazardous components, the effects of the inclusion rate of combustion improver (sodium citrate and potassium citrate) in cigarette paper on the deliveries of seven harmful components, including CO, HCN, NNK, NH₃, B[a]P, phenol and crotonaldehyde, in mainstream cigarette smoke were investigated. The results showed that: 1) Increasing the proportion of potassium citrate in combustion improver, the deliveries of NH₃, phenol, B[a]P, CO and HCN decreased, NNK increased slightly while that of crotonaldehyde had no obvious change. 2) With the increase of combustion improver content in cigarette paper, the deliveries of NH₃, phenol and B[a]P decreased significantly, while that of crotonaldehyde and NNK had no obvious change; CO and HCN increased when that content lower than 10 %, however, decreased when potassium citrate content higher than 40 %. 3) The change of puff number induced by combustion improver was one of the reasons causing the change of deliveries of the seven harmful components.