To explore the micro ecological mechanism of the TCM theory “lung and large intestine are exteriorly and interiorly related”via observing the synchronous dynamic change of microecology of respiratory and intestinal passage of rats with ulcerative colitis. Methods： The ulcerative colitis rat models were created by TNBS (trinitro-benzene-sulfonic acid). We synchronously detected total aerobic bacteria, anaerobic bacteria, enterobacterium, enterococcus, staphylococcus, clostridium perfringens, bifidobacterium and lactobacillus in respiratory and intestinal passage on the 8th day, the 29th day and the 50th day after molding. Results： Dysbacteriosis appeared among the rat models including probiotics decreased and conditional pathogenic bacteria increased. Meanwhile, part of the respiratory floras of the model rats also appeared certain relative changes. Aerobe total and staphylococcus synchronously increased both in lung and large intestine on the 8th day while anaerobe total and enterobacterium increased in intestine but decreased in lung. Aerobe total and staphylococcus synchronously decreased both in lung and large intestine at the 29th day while anaerobe total and enterobacterium decreased in intestine but increased in lung. Aerobe total, anaerobe total and staphylococcus synchronously increased both in lung and large intestine at the 50th day. Conclusion： Rats with enteropathy also can suffer from changes of respiratory floras. Parts of the respiratory and intestinal floras of rats with enteropathy appear synchronous changes during the process of enteropthy affected lung. It may increase or decreased synchronously. Changes in microbial floras can be one of the mechanisms and forms of “enteropathy affected lung”.