This paper deals with the influence of intestinal bacteria on common carp (Cyprinus carpio) and bacterial amylases on the host digestion. Sixty three strains of bacteriahave been isolated from carp intestines and intestinal foods in this connection. Thedistribution of amylase and hemolysin producing strains among the intestinal bacteria has also been investigated. The distribution of amylase producing strains is broad，while that of hemolysin is narrow，and these hemolysin producing strains are not lethal to fish. These results indicate that there were no pathogens among the intestinal bacteria obtained in this experiment. Furthermore，the carp amylase had an apparent optimal pH of 7. 6 and worked well between 7. 2 to 8. 0. The CCI 139 (one strain whose production of amylase was higher than that of other strains)amylase had an apparec}t optimal pH of 8. 8 and worked well between 8. 4 to 9. 4，while the pH of instestinal mixture ranged from 6. 0-7. 0. Finally，the in situ reaction of amylases after SDS-PAGE has convinced that there were bacterial amylases in carp intestinal mixture. The results mentioned above show that there are stable microflora in common carp intestines and bacterial amylases play a promoting effect on starch digestion by host.