Abstract: In order to find methods to selectively reduce tar and harm in cigarette, chitoson dissolved in organic acid solution was added into filter, and the removal of B a P and phenol in mainstream smoke were investigated.Firstly, chitoson solubility in four organic acid solutions was explored.According to the solubility laws and effect of acid on the smoke flavor, lactic acid solution was chosen.Then the influences of chitoson adding content, deacetylation degree ( D.D.) and acid concentration on BaP and phenol removal were discussed.The results showed that, in the range of the experiments, acid type, concentration of lactic acid, and deacetylation degree and adding content of chitoson all had evident influences on removal efficiency of BaP, phenol.