The goal of this study was to evaluate the radial mechanical property of the small-diameter polyurethane vascular grafts reinforced by weft-knitted tubular polyester/spandex fabrics. The polyester/spandex tubular fabrics with different blend ratios were prepared on a weft-knitting machine to reinforce small-diameter polyurethane vascular grafts. Phase separation technique was employed to produce coaxial three-layer small-diameter polyurethane vascular grafts at room temperature. Morphology of the polyurethane vascular grafts was examined by scanning electron microscope (SEM), and micropores were observed on both inner and cross section surfaces. Radial tensile property and compliance of small-diameter polyurethane vascular grafts with and without reinforcement by polyester/spandex tubular fabrics were characterized. The effect of polyester/spandex tubular fabric on the mechanical property of polyurethane vascular grafts was studied. The results indicated that the radial tensile strength of the vascular graft was improved by the tubular fabric, and that the influence of tubular fabric on compliance was small compared to that of wall thickness. It was notable that the wall thickness of the vascular grafts was a major factor in controlling the compliance in the radial direction. Therefore, a coaxial three-layer small-diameter polyurethane vascular graft with excellent compliance and tensile strength could be obtained by controlling the wall thickness and using polyester/spandex fabric as reinforcement. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 100B: 342–349, 2012.