Aim To research the expression level of scavenger receptor BⅠ(SR-BⅠ) in endothelial cells under low laminar shear stress,and to investigate the possible role of SR-BⅠ on the formation of atherosclerosis. Methods The fresh fetal umbilical cord were taken from the health parturient women,and the human umbilical vein endothelial cell(hUVEC) were cultured.The second to fourth generations of endothelial cells will be used in the experiment and then the endothelial cells were planted on the glass slide.After the cell covering the glass slide completely,the glass slide was put in the flow chamber system.The endothelial cells was dealt with different shear stress: the control group was not dealt with shear stress,the dealt group was dealt with the low shear stress(4.2 dyne/cm2).The two groups were treated for 1 h,2 h,4 h and 8 h.Taking the glass slide out of the flow chamber system,total RNA was extracted and the expression level of the SR-BⅠ was detected with RT-PCR and agargel electrophoretic analysis according to the operation instruction of the RT-PCR box. Results The expression of SR-BⅠ became weaker and weaker when it was stimulated continuously by the low shear stress(4.2 dyne/cm2),the lowest expression of SR-BⅠ was at the 8 h,and it almost didn't appear in the electrophoresis picture. Conclusion The expression of SR-BⅠ decreased when it was treated by low shear stress.The harmful mechanism of the low shear stress is that it can reduce the anti-transfer of the cholesterin through decreasing the expression of the SR-BⅠ,and increase the incidence of atherosclerosis.