Diabetic patients often have lipid metabolism disorders, which can lead to life-threatening complications. In this study, we investigated the regulatory effects of polysaccharides extracted from Arctium lappa L. on lipid metabolism in diabetic rats. We constructed a diabetes mellitus mouse model with streptozocin, and treated the rats with A. lappa L. polysaccharide. The body weight analysis showed that the weight of diabetic rats significantly decreased, but the weight of the rats in the polysaccharide treatment groups increased and the ratio of liver weight to body weight also appeared the well effect (tending to normal group). Serum biochemical analysis showed that total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL), and the ratio of liver weight to body weight showed a downward trend. In addition, compared to TC/HDL, TG/HDL, and HDL/LDL, the relative content of HDL was increased. Meanwhile, we used Western blotting to detect changes in protein kinase C alpha (PKC-α), PKC-β, P-selectin, nuclear factor kappa B (NF-κB), and phosphorylated NF-kB p65 in the liver. The results showed that the A. lappa L. polysaccharides regulated lipid metabolism through the PKC/NF-κB pathway in diabetic rats.