The silk fibroin blend membranes were prepared by adding a small amount of poly (vinyl alcohol) (PVA) and heparin. By controlling the preparation conditions, the tensile strength and elongation at break reached to 8.86 MPa and 231.8%, respectively. Meanwhile the in vitro antithrombogenecity significant increased. The clot times (APTT, TT and PT) all exceeded the measurement limit of clot detection instrument. It is expectable using these natural materials to prepare small caliber vessel.