〔Abstract〕 Objective To study the clinical efficacy of Jinmai Wendan Decoction in the treatment of type 2 diabetes mellitus (T2DM). Methods 62 T2DM patients admitted to Fuzhou Second Hospital affiliated to Xiamen University from November 2018 to December 2020 were selected and divided into observation group and control group according to different treatment plans, with 31 cases in each group. The control group was treated with conventional western medicine, and the observation group was treated with Jinmai Wendan Decoction on the basis of the control group. The clinical efficacy and intestinal flora of the two groups were compared. Results The total effective rate of observation group was 93.55 %, which was higher than that of control group (70.97 %), the difference was statistically significant (P < 0.05). Before treatment, there was no significant difference in fasting blood glucose (FPG), 2h postprandial blood glucose (2h PG) and glycosylated hemoglobin (HbA1c) between 2 groups (P > 0.05). After treatment, FPG, 2h PG and HbA1c in the observation group were lower than those in the control group, with statistical significance (P < 0.05). Before treatment, there was no significant difference in the number of firmicutes, enterococcus and bifidobacteria between 2 groups (P > 0.05). After treatment, the number of firmiculosis and enterococcus in the observation group was lower than that in the control group, and the number of bifidobacteria was higher than that in the control group, with statistical significance (P < 0.05). Before treatment, there was no significant difference in C-reactive protein (CRP) and tumor necrosis factor (TNF -- α) between 2 groups (P > 0.05). After treatment, CRP and TNF -- α in the observation group were lower than those in the control group, and the difference was statistically significant (P < 0.05). Conclusion Jinmai Wendan Decoction is effective in treating T2DM patients. It can effectively reduce blood glucose, improve intestinal flora and reduce inflammation.