Panax notoginseng saponins (PNS) is an active ingredient extracted from the roots of Panax notoginseng,which is widely used in the treatment of atherosclerotic diseases.However,its related mechanism is not completely clear.In this study,we found that PNS has the function of improving blood lipid and inhibiting the formation of atherosclerotic plaque in ApoE^-/- mice.Its molecular mechanism is related to TLR4/SYK signaling pathway.Furthermore,in vitro cell experiments showed that PNS could inhibit macrophage phagocytosis and CD36 expression in mouse plaques.Therefore,we believe that PNS can inhibit the formation of foam cells in ApoE^-/- mice by inhibiting TLR4/SYK signaling so as to inhibiting the progression of atherosclerosis.