ObjectiveTo explore the composition of intestinal microbiota between patients with fixed airflow obstruction asthma, reversible airflow obstruction asthma, and healthy control, and analyze the correlation between key differential bacterial distribution and clinical characteristics. MethodsFifteen patients with fixed airflow obstruction asthma (FAO) and 13 patients with reversible airflow obstruction asthma (RAO) were included, along with 11 matched healthy control subjects. Clinical data were collected, and lung function tests and induced sputum examination were performed. Blood and stool samples were tested to compare the gut microbiota status among the groups, and analyze the relationship between gut microbiota abundance and patients' blood routine, IgE levels, lung function, and induced sputum. Results The dominant bacterial compositions were similar in the three groups, but there were differences in the abundance of some species. Compared to the RAO group, the FAO group showed a significant increase in the genera of Bacteroides and Escherichia coli, while Pseudomonas was significantly decreased. The phylum Firmicutes was negatively correlated with the course of asthma, while the phylum Bacteroidetes and genus Bacteroides were positively correlated with the asthma course. Bacteroidetes was negatively correlated with Pre-BD FEV1/FVC, Pseudomonas was positively correlated with Pre-BD FEV1, Escherichia coli was negatively correlated with Post-BD FEV1/FVC, and Bacteroides was negatively correlated with Post-BD MMEF. The class Actinobacteria and the order Actinomycetales were negatively correlated with peripheral blood EOS%, while the order Enterobacteriales and the family Enterobacteriaceae were positively correlated with peripheral blood IgE levels. Furthermore, Actinobacteria and Actinomycetales were negatively correlated with induced sputum EOS%. Conclusions There are differences in the gut microbiota among patients with fixed airflow obstruction asthma, reversible airflow obstruction asthma, and healthy individuals. Bacteroides and Escherichia coli are enriched in the fixed airflow obstruction asthma group, while the Firmicutes are increased in the reversible airflow obstruction asthma group. These three microbiota may act together on Th2 cell-mediated inflammatory responses, influencing the process of airway remodeling, and thereby interfering with the occurrence of fixed airflow obstruction in asthma.