Objective:To study the biomechancial properties of human umbilical cord vein with aging changes and to pro-vide theoretic evidence for clinic in collecting suitable blood graft.Method:33fresh human umbilical cord vein s were collected.The parameters such as pressure,diameter and capacity of blood were also tested,then the com-pliance and elastic mudules were calculated.Result:The P-V curve are highest in37-40weeks while that of elatic mudules are lower,so compliance are best in this period.Conclusion:the author suggest that the umbili-cal vein in37-40weeks should be selected as graft material.