In order to investigate the effect and mechanism of Agaricus blazei Murill polysaccharide on reducing blood lipid in hyperlipidemic rats, the crude polysaccharide was extracted by water extraction and alcohol precipitation method, and the polysaccharide was graded by DEAE cellulose ion exchange column chromatography. The monosaccharide composition was analyzed by high performance liquid chromatography, and the content of polysaccharide was determined. The rats were randomly divided into four groups:blank control group, model group, simvastatin positive control group, Agaricus blazei Murill polysaccharide group, and oral administration for 42 days. The contents of total cholesterol (TC), triglyceride (TG), low density lipoprotein cholesterol (LDL-C) and high density lipoprotein cholesterol (HDL-C) in serum were detected by ELISA. HE staining method was used to observe the pathological changes of liver tissue, and the mRNA levels of LDL-R, SREBP-1C, CYP7a-1, PPAR - α and SCARB-1F were detected by RT-PCR. The results showed that the content of sugar in Agaricus blazei polysaccharide was 75.1%, and ABP-A contained 88.6 GLc, 2.4% Gal, 1.9% Man, 1.0% Rha, 0.5% GalA, 1.9% Xyl, 2.1% Ara, and 1.6% Fuc. ABP-A significantly decreased liver index (P<0.05), and serum TC, TG, LDL-C (P<0.01), but significantly increased HDL-C (P<0.01), lipid droplets deposition in liver was decreased by ABP-A. LDL-R, SCARB-1F mRNA expression (P<0.05) and CYP7a-1, PPAR - α mRNA levels (P<0.01) significantly increased, and SREBP-1C mRNA expression dramatically decreased (P<0.01) .These results indicated that ABP-A exerted significant effects on lowering blood lipid, and the mechanism may be related to regulate the expression of LDL-R, SREBP-1c, CYP7a-1, PPAR-α and SCARB-1F.