IgA Nephropathy (IgAN) is a serious threat to human health. The exact pathogenesis of IgAN has not been elucidated yet. Currently, there is no specific and effective treatment except supportive therapy based on renin angiotensin system inhibitor. IgAN is characterized by IgA deposits in the mesangial of the kidney, persistent hematuria, and often associated with respiratory or gastrointestinal infections. Recent studies have shown a link between human genetics, gut microbiology and the pathogenesis of IgAN. Patients with kidney disease are often accompanied by intestinal flora disorder, and intestinal flora disorder will accelerate the process of kidney disease. In recent years, multiple omics studies have found that mucosal microbial immunity is involved in the pathogenesis of IgAN, among which respiratory tract and digestive tract infections can cause or aggravate IgAN. Sporadic studies have shown that intestinal microbiome diversity in IgAN patients is lower than that in normal subjects. In IgAN patients, the abundance of beneficial bacteria such as Clostridium, Enterococcus and Lactobacillus is significantly reduced. The abundance of Ruminococcus, Lachnospiraceae and Streptococcaeae increased significantly. Previous studies by the research team confirmed a strong correlation between human genetic background, intestinal microecology, and IgAN pathogenesis. Nine Single nucleotide polymorphisms (SNPS) were associated with IgAN in 1511 IgAN patients and 4469 healthy controls. Among them, the dangerous type of genes and the intestinal bacteria (Dialister/Bacilli) reduce harmful bacteria and is associated with increased (Erysipelotrichaceae/Lachnobacterium). Using metagenomic high-throughput sequencing technology, the team further studied the intestinal microflora structure at the species level in 16 IgAN patients confirmed by biopsy and 32 healthy individuals, and showed significant differences in composition and relative abundance between the two groups. The abundance of Ruminococcus gnavus, a subgenus of Ruminococcus, increased significantly in IgAN patients. Correlation analysis showed that there was a significant positive correlation between active rumen coccus and serum IgA and pathological severity in IgAN patients. Fecal microbiota transplantation (FMT) refers to the transplantation of functional flora from the feces of a healthy person into the gastrointestinal tract of a patient, thereby reestablishing the intestinal flora with normal function. FMT promotes the treatment of intestinal microecology by eliminating single microorganisms or certain pathogens (such as vaccines and antibiotics) and increasing beneficial bacteria (such as prebiotics and beneficial bacteria) to the reconstruction of intestinal microecology. The best treatment indication for FMT is Clostridium difficile infection, which is a treatment choice confirmed by expert consensus and guidelines in many countries and regions. Meanwhile, FMT has been used in the treatment and research of many intestinal microbiome related diseases worldwide. Since the occurrence of IgAN is related to intestinal flora, we attempted to conduct fecal bacteria transplantation by using FMT capsules in patients with IgA nephropathy, so as to explore the effectiveness and safety of FMT in the treatment of IgA nephropathy.