Objective To compare and analyze the auxiliary preventive and therapeutic lipid?lowering effects of Antarctic krill oil on high?fat high?cholesterol diet?induced hyperlipidemia rat models. Methods Forty?eight 5 - 6?week old SPF male Sprague?Dawley rats were divided into four groups: the blank normal group, hyperlipidemia model group, krill oil prevention group and krill oil treatment group. The rat model of hyperlipidemia was established by high?fat high cholesterol diet feeding. The krill oil prevention group was continuously administered krill oil for 14 days before and 12 days during the establishment of hyperlipidemia models. Meanwhile,the krill oil treatment group received krill oil for 12 days only during the hyperlipidemia modeling period. Serum total cholesterol (TC), triglyceride (TG), high?density lipoprotein cholesterol (HDL?C), and low?density lipoprotein cholesterol (LDL?C) in the rats were measured and pathological examination of liver tissues was performed to assess and compare the preventive and therapeutic effects of krill oil on hyperlipidemia and hypercholesterolemia in the rats. Results The preventive administration of krill oil significantly reduced serum TC and LDL?C ( P < 0. 05), paralleled by the milder fatty degeneration of liver tissues, while no significant changes of serum TG and HDL?C ( P > 0. 05). After therapeutic administration of Antarctic krill oil, there was no significant difference in serum concentration of TC, TG, HDL?C and LDL?C ( P > 0. 05) compared with the model group, and no significant auxiliary lipid?lowering effect was observed on the hyperlipidemia rats. Conclusions There is a significant auxiliary lipid?lowering effect and reducing serum total cholesterol after preventive administration of Antarctic krill oil.