The objective of this paper was to investigate the effects of different protein feeds on growth parameters of Ruminobacter amylophilus in rumen. Four Xuhuai white goats fitted with rumen cannula, were assigned randomly in a 4×4 Latin square, and were fed with 4 protein supplementation diets which were plume meal group, corn gluten meal group, soybean meal group, and fish meal group, respectively. The Real-time PCR technique was introduced to determine the quantity of Ruminobacter amylophilus. The results showed that NH3-N concentration was the highest in soybean meal group, and significantly higher than that in the other 3 groups (P<0.05). No significant difference was found in total amount of bacteria among all groups (P>0.05); while both Ruminobacter amylophilus density and the percentages of Ruminobacter amylophilus in all bacteria were the highest in soybean meal group, and there were significant differences among all groups (P<0.05). In conclusion, soybean meal feed was suitable for Ruminobacter amylophilus growth, and real-time PCR technique was a powerful method for ruminal microorganism quantity analysis.［Chinese Journal of Animal Nutrition, 2010，22（2）:327-334］