A single factor experiment was adopted to investigate the effects of dietary amylose/amylopectin ratio on blood biochemical parameters and hindgut microbial flora of yellow broilers. Three hundred and twenty 29-day-old female yellow broilers were randomly allocated to 4 groups with 5 replicates per group and 16 broilers per replicate. Four diets with amylose/amylopectin ratios of 0.11, 0.23, 0.35 and 0.47 were available ad libitum. The experiment lasted for 28 days. The carcass traits, blood biochemical parameters and hindgut microbial flora of broilers were measured. The results showed that the dietary amylose/amylopectin ratio had significant effects on abdominal fat percentage （P<0.01）, postprandial 0.5 h blood glucose and insulin concentration of broilers （P<0.05）, but there were no significant effects on blood lactate acid and urea nitrogen concentration of broilers （P>0.05）. Hindgut microbial flora analysis showed that increasing dietary amylose/amylopectin ratio significantly increased the number of Enterococcus, Lactobacillus and Bifidobacteria （P<0.05）, while significantly reduced the number of Escherichia coli in hindgut of broilers （P<0.05）. It suggested that the difference of dietary amylose/amylopectin ratio could change the relationship of in vivo glucose release rate and amino acids metabolism, which led to the change of blood biochemical parameters and hindgut microbial flora of yellow broilers, and an appropriate dietary amylose/amylopectin ratio could contribute to the improvement of carcass traits and keep microbial flora balance in hindgut of broilers.［Chinese Journal of Animal Nutrition, 2010，22（4）:904-910］