The relationship between lactic acid bacterial flora and congenital megacolon small bowel colitis was initially investigated by testing bifidobacteria and lactobacilli in the stools of children with megacolon small bowel colitis, children without enterocolitis and normal children. A total of 3 children, 1 month to 7 years old, underwent congenital megacolon radical surgery at the medical school in February I year? The mean age was 1,2 years. According to the presence or absence of clinical symptoms of small bowel colitis before and after surgery, they were divided into HD small bowel colitis group and HD non-enteritis group Among them, 1 case of enteritis. And 1 case of the same age was selected as the normal control group. Fresh stools were collected from each group separately. The stools were immediately placed in sterile centrifuge tubes. The DNA of the bacterial genome was extracted from the stool within 24 h. Since the absolute values of bifidobacteria and lactobacilli in the stool were not normally distributed, the logarithmic values (1og ) were taken for ANOVA. The log content of bifidobacteria in each group: 7.07±0.85 in the megacolon enteritis group compared with 8.36±0.80 in the megacolon non-enteritis group and 8, 46±0.92 in the normal control group. The differences were all statistically significant (P<(). 05). Macrocolonic non-enteritis group and normal control group were similar and the difference was not statistically significant. The log content of lactobacilli in each group: 5.51±0.65 in the giant colitis group and 5.79±0.82 in the giant colitis non-enteritis group were statistically significant (P (1.05)) compared with 6.47±0.71 in the normal control group, respectively. Conclusion Combined with the results of this experiment suggest that the content of bifidobacteria and lactobacilli in children with megacolon is significantly lower than in the normal group, which may be one of the reasons for the occurrence of enterocolitis.