This experiment was conducted to investigate the effects of different Eucommia leaves extract level on growth performance and immune function of Arbor Acre (AA) broilers.A total of 275 one-day-old AA broilers were randomly divided into 5 groups with 5 replicates per group and 11 chickens per replicate. Broilers in the control group were fed a basal diet, and the other were fed the basal diets supplemented with 0.05%, 0.10%, 0.15% and 0.20% Eucommia leaves extract, respectively. The feeding trial lasted for 42 days. The results showed as follows: 1) there was no significant difference on the average daily feed intake among all groups (P>0.05). Compared with the control group, 0.15% supplemental group increased average daily gain (ADG) by 7.42% during 8 to 14 days (P<0.05), and 0.05%, 0.10% and 0.15% supplemental groups increased ADG by 26.13%, 25.05% and 24.94% during 29 to 35 days (P<0.05), and the feed to gain ratio of 0.05% and 0.15% supplemental groups decreased by 21.15% and 19.34% during 29 to 35 days (P<0.05). 2) There was no significant difference on immune organs index and serum immunoglobulin A content among all groups at 21 and 42 days (P>0.05). Compared with the control group, the serum immunoglobulin G content in 0.15% supplemental group increased by 23.06% at 21 days (P<0.05), and the serum immunoglobulin M content in 0.05%, 0.15% and 0.20% supplemental groups increased by 118.89%, 73.33% and 71.11% at 42 days (P<0.05).In conclusion, dietary supplemented with Eucommia leaves extract can improved growth performance and immune function of broilers, and the suitable supplemental level is 0.15%.