Abstract：Objective：To investigate the effect of Dendrobium candidum powder on the improvement of pancreatic islet function in patients with type 2 diabetes mellites(T2DM). Methods： 110 patients with T2DM were randomly divided into observation group and control group，55 cases in each group. The observation group was treated with Dendrobium candidum powder，and the control group was treated with placebo. After 2 months of treatment，the clinical effects of the two groups were compared. Results：After treatment，the total clinical effective rate of the observation group was 89.09%，which was higher than 3.64% of the control group. The difference between the two groups was statistically significant(P＜0.05). Before treatment，there was no significant difference in the scores of TCM syndromes between the two groups(P＞0.05)； the scores of TCM syndromes in the observation group were significantly lower than those before treatment and the control group(P＜0.05)，while the scores of TCM syndromes in the control group before and after treatment there was no significant difference(P＞0.05). Before treatment， the fasting blood glucose(FBG)， postprandial 2 h blood glucose(P2hBG) and glycosylated hemoglobin(HbA1c) levels of the two groups were similar(P＞0.05). After treatment，the levels of FBG，P2hBG and HbA1c in the observation group were significantly lower than those before and after treatment in the control group(P＜ 0.05)， while the levels of FBG， P2hBG and HbA1c in the control group were not different before and after treatment(P＞ 0.05). Before treatment，the pancreatic islet function indexes fasting insulin(FINS) and 2 h insulin(2hINS)，insulin resistance index(Homa-IR) and insulin cell function index(Homa-β) levels before treatment in the two groups，there was no significant difference(P＞0.05). After treatment，the levels of FINS，2hINS，and Homa- β in the observation group were significantly higher than those before treatment and the control group， and the levels of Homa- IR were significantly lower than those before treatment and the control group(P＜0.05). There was no significant difference in the levels of FINS，2hINS，Homa-IR and Homa-β in the control group before and after treatment(P＞0.05). Conclusion： Treatment of T2DM patients with Dendrobium candidum powder has satisfactory results. It can effectively relieve clinical symptoms，control blood sugar and improve islet function.