Abstract: The objects of this experiment was to study the effects of condensed tannin on growth performace, volatile fattt acid contents and bacterial flora in rumen of Nubian goats, 16 Nubian goats with an average body weight of（25.78±1.79） kg with good growth were randomly divided into control group and treatment group with 2 replicates per group and 4 goats per replicate. Goats in the control group were fed with basal diet and treatment group were added 4% condensed tannin in the basal diet. The pre-feeding period lasted for 7 days, and the experiment lasted for 50 days. At the end of the experiment, the differences in growth performance indicators（average daily weight gain, average daily feed intake and feed-to-weight ratio）, the content of volatile fatty acids（acetic acid, butyric acid, isobutyric acid, isovaleric acid, propionic acid and valeric acid） in rumen fluid, the ratio of acetic acid and propionic acid, and bacterial flora in rumen fluid were analyzed between the two groups of test sheep.The results showed that feed-to-weight ratio in treatment group was lower than that of control group（P＜0.05）. Acetic acid, butyric acid, isobutyric acid, isovaleric acid, propionic acid and valeric acid in control group were significantly higher than those in treatment group（P＜0.05）, and the ratio of acetic acid and propionic acid in treatment group was significantly higher than that in control group（P＜0.05）. OUTs（5 925） were lower than that in the control group（6 906）. The Shannon index, Chao1 index and Observed_species index in the treatment group were significantly lower than those in the control group（P＜0.05）. At the phylum level, compared with the control group, the relative abundance of Bacteroidetes, Bacteria_unclassified, and Proteobacteria in the rumen of Nubia goats in the treatment group decreased by 2.60%,11.15%, and 14.07%, respectively, and the relative abundance of Firmicutes increased by 19.22% compared with the control group. At the genus level, the relative abundance of Paraprevotella in the rumen of Nubian goats in the treatment group was 33.36% higher than that in the control group, while the relative abundance of Bacteroidales_unclassified in the treatment group was 24.63% lower than that in the control group. The abundance of norank f Bacteroidales RF16 group, Ruminococcaceae_unclassified, Bacteria_unclassified, Rikenella, Succiniclasticum, Porphyromonadaceae_unclassified of treatment group was lower than control group. The results indicated that 4% level of condensed tannin significantly reduced the feed-to-weight ratio of Nubia goats, inhibited carbohydrate fermentation in the rumen of Nubian goats, and had inhibitory effect on most bacteria in the rumen, but had promoting effect on Firmicutes and Prevotella.