Choosing the diameter is one of the basic problems of autogenous vein graft. In order to achieve theobject that the inner diameter of autogenous vein graft is equal to that of artery under the arterial pressure, we analyze the method for choosing the diameter of autogenous vein graft, by considering the effects of the longitudinal stretch ration and blood pressure on the diameter, the wall thickness and the pressurediameter relationship. Using the data from the rabbit femoral arteries and veins, we can know that the longitudinal stretch ratio and the diameter of artery have some effects on choosing the diameter of autogenous vein graft.