Objective To investigate the relationship between Treg/Th17 immune imbalance and intestinal microflora in patients with rheumatoid arthritis complicated with pulmonary interstitial disease (RA-ILD). Methods 100 patients with RA treated in our hospital from June 2021 to June 2022 were selected and included in the RA group. According to the clinical symptoms, X-ray and chest HRCT examination, the RA group was divided into RA-ILD group (n=39) and NO-ILD group (n=61). The clinical data and laboratory indexes of the two groups were collected. Treg/Th17 cells and related factors were detected. The fecal DNA was collected and extracted, and the 16s rRNA V3-V4 region of the samples was sequenced by Illumina Miseq sequencing platform, and the sequencing data were analyzed by bioinformatics. Spearman correlation analysis was used to test the correlation between intestinal flora abundance and Treg/Th17 in patients with RA-ILD. Results Compared with NO-ILD group, the Shannon index, Observed species index and Chao1 index of RA-ILD group were significantly lower, the relative abundance of Bacteriodetes, Haemophilus, Acuformic-Prevot, Firmicutes, Eubacterium, Lactobacillus and Veronella were significantly lower, and the relative abundances of Bacteroides, Proteus, Gordonella, actinomycetes, Prevos were significantly higher, and the proportion of Treg cells and Treg/Th17 were significantly lower. The levels of IL-23, IL-17 and the proportion of Th17 cells were significantly higher (P<0.05). Treg/Th17 was correlated with the relative abundance of Clostridium,Virococcus, Lactobacillus, Haemophilus, Haemophilus, Bacterium and Pleurota (P<0.05), and negatively correlated with Clostridium, Gordonella, Prevotella,Proteus, Actinomycetes and Bacteroides (P<0.05).Conclusion There is an imbalance in the proportion of Treg/Th17 cells in patients with RA complicated with ILD, and the imbalance of intestinal flora may be the main reason for the imbalance