In order to evaluate the effect of Lonicerae flos as a feed additive on blood biochemical indexes and immune function of yellow-feather broilers (Gallus gallus domesticus), a total of 150 two-day-old healthy yellow-feather broilers were randomly divided into 5 experimental groups for a 42-day experiment. The 1st day to the 10th day was the environmental adaptation period, the 11th day to the 26th day (12～27 days old) was the experimental phase Ⅰ, and the 27th day to the 42nd day (28～43 days old) was the experimental phase Ⅱ. Yellow-feather broilers in the 5 groups were fed the same basal diet every day, the control group (CK group) was fed with drinking water without L. flos components every day, the four L. flos treatment groups, namely T1, T2, T3， and T4 groups, were fed with drinking water without L. flos components during the environmental adaptation period, and were fed with L. flos water extract diluents with the mass fractions of 1.0%, 1.5%, 2.0%, and 3.0% of the original medicinal materials in the experimental Ⅰ and Ⅱ periods to replace drinking water. The mass concentrations of total protein, albumin and globulin, the activities of alanine aminotransferase, aspartate aminotransferase and γ-glutamyl transferase, the concentrations of total bile acid, creatinine, uric acid, total cholesterol, triglyceride and glucose, and the concentrations of immunoglobulin IgG and IgA in the blood samples of yellow-feather broilers were measured at the end of phases Ⅰ and Ⅱ, respectively. And the weight of bursa of fabricius, spleen and thymus was measured and the immune organ index was calculated. The results obtained showed that there was no significant difference in the mass concentration of total protein, globulin and γ-glutamyltransferase activity in the blood samples of the five groups of yellow-feather broilers. Compared with the CK group, the total bile acid concentration and aspartate aminotransferase activity in the blood samples of yellow-feather broilers were significantly decreased by feeding the water extract diluents of L. flos with the mass fractions of 1.0%, 1.5%, and 3.0% of the original medicinal materials. The uric acid concentration in the blood samples of yellow-feather broilers was significantly decreased by feeding the water extract diluents of L. flos with the mass fractions of 1.5%, 2.0%, and 3.0% of the original medicinal materials. The water extract diluent of L. flos increased the immune organ index of yellow-feather broilers and increased the mass concentration of serum IgA and IgG. The results indicated that feeding the water extract diluents of L. flos with the mass fractions of 1.5% of the original medicinal materials could effectively promote the growth of yellow-feather broilers and improve the blood biochemical indexes and immune function of yellow-feather broilers.