Abstract: Children with steroid dependent nephrotic syndrome（SDNS） have higher risk of obesity than healthy children, but the mechanism is unclear. Dysbiosis of gut microbiota can promote the development of obesity. 26 SDNS children and 26 age-and sex-matched healthy（H） children were recruited in this study. The body mass index（BMI） of SDNS children was significantly higher than that of healthy children. The gut microbiota of SDNS and healthy children was compared with Illumina MiSeq high-throughput sequencing of 16S rRNA gene V3-V4 region. The composition of the gut microbiota was significantly different between the two child groups. The butyrate-producing bacteria decreased in SDNS children, including Faecalibacterium, Roseburia, Coprococcus, Butyricicoccus, Lachnospira and Lachnospiraceae NK4A136 group, and the pathogenic bacteria Actinomyces increased. Faecalibacterium, which is both butyrate-producing and anti-inflammatory, and pathogenic bacteria Actinomyces were significantly negatively and positively correlated with BMI, respectively. Metabolic pathway prediction analysis showed that sugar metabolism pathways of the gut microbiota were up-regulated in SDNS children. Co-occurrence network analysis result showed that the complexity of ecological interaction network of gut microbiota increased in SDNS group compared to that of healthy children. The results showed that the dysbiosis of gut microbiota, characterized by reduced abundance of butyrate-producing bacteria and increased abundance of pathogenic bacteria, in SDNS children is significantly associated with their abnormal increase of BMI. This work warrants further study on the causal relationship between gut microbiota dysbio-sis and obesity in SDNS children, and the exploration of the possibility to prevent obesity in SDNS children by regulating gut microbiota.