Objective To judge the effect of hemodynamic characteristics on flow vessel of double bifurcation collateral by numerical calculation. Method A kind of double bifurcation collateral flow vessel’s hemodynamic characteristics such as blood flowing velocity vector, the shear stress and pressure at the vessel wall were calculated, studied and compared by the boundary element method. The lesions caused and developed by hemodynamic reasons were logically explained. Whether the hemodynamic characteristics of the branch would be affected by the lesion in the primary branch vessel was judged based on calculation results of the shear stress and the pressure at the branch vessel wall before and after the lesions. Results In the primary branch vessel, the blood velocity and shear stress increased obviously if the lesion appeared to narrow the vessel. Although the blood velocity and the shear stress in the branch vessel were not affected by the lesion, but its blood pressure became high. Conclusions The blood hydrokinetic characteristics play an important role in the cause and development of cardiovascular diseases. The atherosclerosis could be caused in the branch vessel of double bifurcation arterialvessel as the lesion becomes more serious in its primary branch vessel.