This study was conducted to evaluate the effects of supplemental plant essential oil mixtures in broiler diets on performance, intestinal microflora and intestinal mucosa morphology. Arbor Acres chicks (n=600, 1-day-old, male) were randomly allotted into 5 treatments, each treatment consisted of 8 replicates with 15 birds each. Five treatments consisted of no addition of EOM or antibiotic (control group), 20 mg/kg aureomycin, 40, 80 and 160 mg/kg EOM in the corn-soybean meal diets. The results showed that EOM was tended to improve the growth performance during the whole experimental period, although the effects were not significant (P>0.05). EOM increased Lactobacillus number in ileum (d 21) and caecum (P<0.05). The supplementation of 160 mg/kg EOM reduced E. coli number in ileum (d 43) and caecum (P<0.05) as well as S.aureus number in ileum and caecum (P<0.05). EOM increased villus height to crypt depth ratios in ileum (d 21) (P<0.05). The results indicate that EOM has the function of improving growth performance and regulating microflora as well as intestinal mucosa morphology. The appropriate supplemental amount of EOM is 160 mg/kg under this experimental condition.［Chinese Journal of Animal Nutrition，2011，23（3）：433-439］