In order to explore functional properties of phytosterol extracted from Cortex mori, scavenging ability for nitrite was determined under different conditions, such as phytosterol concentration , reaction time, reaction temperature and pH. The results showed that nitrite scavenging rate reached 72.65% when concentration of phytosterol was 0.80 mg/mL. At this concentration, the nitrite scavenging rate reached the maximum under the following conditions: reaction time of 60 min, reaction temperature of 65 ℃ and pH of 3.0 by the single factor tests. Then antibacterial activities and mechanism of phytosterol from Cortex mori were also discussed. The antimicrobial effects against various bacterial and mold strains were tested by filter paper method. Effects of phytosterol from Cortex mori against Escherichia Coli were obtained by determination of bacterial growth curves, bacterial protein content and conductivity of bacterial suspension solution. MIC of phytosterol against E. coli was 10.0 mg/mL. Phytosterol from Cortex mori inhibited bacterial split, cell division, normal metabolism activities of bacterial proteins, and made the change of cell membrane permeability, showing that it inhibited the normal growth of E. coli.