The invention relates to a traditional-Chinese-medicine compound preparation for treating damaged function of the islet of 2-type diabetes mellitus and a preparation method thereof and belongs to the technical field of Chinese medicine treatment of the diabetes mellitus. The invention adopts the technical scheme that the traditional-Chinese-medicine compound preparation is prepared from the following crude drugs in parts by weight: 10-40 parts of rhizoma curcumae longae, 10-40 parts of radix et rhizoma rhei, 5-30 parts of rhizoma alismatis, 5-30 parts of glossy privet fruit, 5-30 parts of grape seed and 5-30 parts of flaxseed. The traditional-Chinese-medicine compound preparation has the beneficial effects that a drug prescription is reasonable, the use is safe, the curative effect is obvious, the side effect is low, the price is moderate, the manufacture is convenient, the drug source is rich, the administration is convenient, the raw materials are easy to obtain, the production process is advanced, the operability is strong, and the effect of reducing blood sugar, blood fat and blood viscosity of a patient with the 2-type diabetes mellitus is achieved.