Abstract: Five-segment cellulose acetate(CA) filter samples were prepared for investigating the sectional retaining efficiency of CA filter to major phenols in mainstream cigarette smoke.The results showed that:1) CA filters possessed good ability for retaining phenols,especially monophenols.2) As the mainstream cigarette smoke flowed towards the mouth end of cigarette during puffing,the monophenols retaining rate in filter versus per unit nicotine yield obviously decreased,while the bisphenols retaining efficiency did not change significantly,which might relate to their different filtration principles.3) The phenols in the order of retaining rate in filter were phenol>o-cresol>m-cresol/p-cresol>catechol/hydroquinone>resorcinol.In view of that the monophenols retaining efficiency significantly decreased from tobacco end towards mouth end,it was suggested that the harm reducing materials should be added to the filter section near the mouth end.