Aim To investigate the function of Sinapis alba extract’s antioxidant ability and regulation of CD36 expression in macrophages,and Sinapis alba extract’s prevention of atherosclerosis. Methods C57/BL6 mice were divided into two groups which were injected with 1.5% normal saline or 1.5% Sinapis alba extract for 0.2 mL/day,respectively. The injection was paused for one day after continuously injected for three days,and then on the 5^th day,mice were sacrificed to collect abdominal macrophages. Plasma superoxide dismutase （SOD） activity and lipid peroxide （LPO） cellular SOD,respiratory burst,LPO,expression of CD36 and neutral fat accumulation were assayed. 30 male ApoE^－/－ mouse were randomly divided into three groups: chew food diet group,high-fat diet group and high-fat diet ＋ 7.5% Sinapis alba group. The mouse were sacrificed 25 weeks later,and aorta was dissected,stained by oil red O. Plaque area was measured by an automatic image analyzer. Results In Sinapis alba extract group,SOD activity was higher and LPO was lower than that in the control group. Sinapis alba extract could reduce macrophage respiratory burst,and LPO level,CD36 expression and neutral fat accumulation induced by ox-LDL. Sinapis alba extract could reduce lipid plaque area by high-fat diet （P<0.05）. Conclusions Sinapis alba extract can effectively improve the body’s antioxidant capacity,improve the antioxidant activity of macrophages,reduce lipid uptake,prevent early atherosclerosis lesions.