At present, most of the first-line drugs for treating diabetes in the world are western medicine, and there is no pure Chinese medicine with recognized good curative effect. Downing Tongluo was discovered when we sorted out and explored the traditional medicine of Miao nationality. Pharmacological and clinical tests show that the drug is safe and effective in treating diabetes. The experimental results made by the Institute of Medicinal Plants of China Academy of Medical Sciences showed that Tang Ning Tongluo significantly reduced the blood sugar level of the two model mice, and the effect was better than that of metformin, reaching the level of first-line western medicine, which had a protective effect on islet β cells, improved insulin resistance and significantly improved diabetic complications. This is very valuable for drugs to treat diabetes.