Abstract: In order to find out a new way to decrease the phenols in MCS, the filtration efficiency to major phenols in MCS by acetate cellulose filters with different triacetin levels was tested. The results showed that:1) The filtration efficiency to monohydric phenols increased with the increase of triacetin level in the filters, though not significantly, while the filtration efficiency to dihydric phenols changed little; 2) The filtration efficiency to monohydric phenols by the filter was obviously higher than that to dihydric phenols, the phenols in the order of filtration efficiency were phenol > o-cresol >(m, p)-cresol > catechol > hydroquinone > resorcinol.