Diabetic nephropathy is one of the most common and severe chronic complications of diabetes, with an increasing incidence rate in China. Therefore, it is urgently necessary to elucidate its pathogenesis in depth and enrich and improve prevention and treatment measures. 1-Deoxynojirimycin is a type of piperidine polyhydroxy alkaloid that can competitively inhibit the activity of intestinal α-glycosidases, which is used to reduce postprandial blood sugar in diabetes; it can also enter the body and play a role in inhibiting the synthesis of sugar chains during viral replication and the modification of glycans in glycoproteins. Research on 1-deoxynojirimycin and its derivatives provides new directions for creating new clinical treatment methods and developing new drugs. This invention provides the application of 1-deoxynojirimycin in the preparation of drugs for diabetic nephropathy, offering an effective combination drug. Experiments have found that 1-deoxynojirimycin inhibits the proliferation of mesangial cells in rats cultured with high glucose. The inhibition of the increase in mesangial cell a-smooth muscle actin expression and the effects on TGF01 and integrin 0 mRNA expression by 1-deoxynojirimycin fully verify the therapeutic effect of 1-deoxynojirimycin on diabetic nephropathy.