The invention discloses health-care food for assisting blood glucose decreasing. The main functional components of the health-care food are three or more than three types of the following raw materials: kelp or kelp extract, potassium alginate (low molecular weight potassium alginate), rhizoma dioscoreae or rhizoma dioscoreae extract, lycium Chinense miller or lycium Chinense miller extract, radix puerariae or radix puerariae extract, folium mori or folium mori extract, rhizoma polygonati odorati extract, momordica charantia extract, cyclocarya paliurus leaf, corn stigma, rhizoma polygonati, radix astragali seu hedysari, radix notoginseng or radix notoginseng extract, rhodiola rosea or rhodiola rosea extract, inulin and citrus fiber powder. A preparation method of the health-care food for assisting the blood glucose decreasing comprises the following steps of 1, crushing and screening; 2, weighing; 3, mixing and stirring. The health-care food for assisting the blood glucose decreasing has the advantages that the effect of assisting blood glucose decreasing is obvious, the safety is good, any side effect is avoided, and complications and side effects caused by long-time administration of western blood glucose decreasing medicines are avoided; the administration is convenient, and the carrying is easy; the action mechanism is clear, the economic and practical effects are realized, and the application range is wide.