Abstract: In order to study the role of ionic liquid as a solvent for whole cell biocatalyst,it is necessary to investigate the effect of ionic liquid treatments on microbial activity. In this study,Saccharomyces cerevisiae was selected as testing target,and the effect of differentBmimPF₆treatments on growth curve,sugar degradation curve,microbial activity,colonial morphology and the shape of cell wall of yeast were studied. The results showed that:BmimPF₆ionic liquid would inhibit the growth of yeast,but the ionic liquid yeast lethal effect was weak,that was totally different from supercritical CO₂ treatment and high concentration benzene methanol treatment which would lead most yeast to death.