In order to investigate the relationship between gut microbiota and type 2 diabetic erectile dysfunction(T2DED), we analyzed the characteristics of gut microbiota in the Sprague-Dawley(SD) rats with T2DED. Thirty-five SD rats were randomly divided into two groups: control group(n=15) with normal diet, and experimental group(n=20) with construction of T2D model. Faecal and serum samples were collected at 2nd and 8th week after establishment of T2D model, respectively. Faecal samples were used for analysis of gut microbiota, and serum samples for detection of trimethylamine N-oxide(TMAO), lipopolysaccharide(LPS), and inflammatory factors like interleukin-1(IL-1), IL-2, IL-10, and monocyte chemoattractantprotein-1(MCP-1). The main compositions of gut microbiota were Bacteroidetes, Proteobacteria and Firmicutes at the phylum level, and Oscillospira, Allobaculum, Bacteroides, Ruminococcus, SMB53, Prevotella, Coprococcus, Sutterella and Blautia at the genus level with relatively higher abundance in all SD rats. The relative abundance of Enterococcus, Corynebacterium, Aerococcus, Facklamia(opportunistic pathogens in most case) increased, and that of Allobaculum, Bifidobacterium, Eubacterium, Anaerotruncus(beneficial bacteria) decreased in T2DED group as compared with that at 2nd week after establishment of T2D model(T2D2 group). The serum contents of TMAO, LPS, IL-1, IL-2, IL-10 and MCP-1 in T2DED group were significantly higher than those in control group. The gut microbiota of T2DED rats was inhibited. The gut microbiota of T2DED rats had changed, as the relative abundance of beneficial bacterium was decreased while that of opportunistic pathogens was increased. The variations of gut microbiota might lead to inflammation and prompt the emergence of erectile dysfunction in the rats with T2D. TMAO might play an important role in the formation of T2DED. In order to investigate the relationship between gut microbiota and type 2 diabetic erectile dysfunction (T2DED), we analyzed the characteristics of gut microbiota in the Sprague-Dawley (SD) rats with T2DED. Thirty-five SD rats were randomly divided into two groups: Control group (n = 15) with normal diet, and experimental group (n = 20) with construction of T2D model. Faecal and serum samples were collected at 2nd and 8th week after establishment of T2D model, respectively. of gut microbiota, and serum samples for detection of trimethylamine N-oxide (TMAO), lipopolysaccharide (LPS), and inflammatory factors like interleukin-1, IL- 2, IL- 10, and monocyte chemoattractant protein- 1 MCP-1). The main compositions of gut microbiota were Bacteroidetes, Proteobacteria and Firmicutes at the phylum level, and Oscillospira, Allobaculum, Bacteroides, Ruminococcus, SMB53, Prevotella, Coprococcus, Sutterella and Blautia at the genus level with relatively higher abundances ance in all SD rats. The relative abundance of Enterococcus, Corynebacterium, Aerococcus, Facklamia (opportunistic pathogens in most case) increased, and that of Allobaculum, Bifidobacterium, Eubacterium, Anaerotruncus (beneficial bacteria) decreased in T2DED group as compared with that at 2nd week after establishment of T2D model (T2D2 group). The serum contents of TMAO, LPS, IL-1, IL-2, IL-10 and MCP- 1 in T2DED group were significantly higher than those in control group. The gut microbiota of The gut microbiota of T2DED rats had changed, as the relative abundance of beneficial bacterium was decreased while that of opportunistic pathogens was increased. The variations of gut microbiota might lead to inflammation and prompt the emergence of erectile dysfunction in the rats with T2D. TMAO might play an important role in the formation of T2DED.