Objective To investigate the compliance of small-diameter medical polyurethane artificial vascular graft, compared the micro-morphology and radical compliance of small-diameter medical polyurethane artificial vascular graft making in dry and wet; explored the effects on radical compliance causing by the sizes of the diameter and thickness of the artificial vascular graft; analysised the differences of compliance between different parts in artificial vascular graft when it was placed in the circulatory system. Methods The small-diameter artificial vascular graft with different morphology and different internal diameter and different wall thickness was prepared by casting polyurethane film onto the glass rod model. We get the pressure-diameter in a custom-designed pulsatile circulatory apparatus, calculate the radial compliance of artificial vascular graft based on the ISO7198 international standard. Results The morphology of artificial vascular graft in dry are dense; but the morphology of artificial vascular graft in wet are microporous which are even in size and distribution. The radical compliance is increasing gradually with the increase of artificial vascular graft diameter; but the radical compliance is decreasing with the increase of wall thickness; the radical compliance is different between the middle and the junctions of artificial vascular grafts, the larger fluctuation value of compliance appears in the export of artificial vascular; artificial vascular in wet have more superior radical compliance than artificial vascular in dry. Conclusions The medical polyurethane small-diameter artificial vascular graft has a excellent compliance, it is a promising materials which to be small-diameter vascular substitute. and there are many factors that will result in radical compliance mismatch, further research in radical compliance will be needed.