Carboxyl ion (COOH+) implantation was performed at 50 keV with different fluences for polypropylene. Hemocompatibility tests show that blood coagulation time and recalcification time of polypropylene were enhanced significantly with the increasing fluence. At the same time, the human endothelial cells grown on the surface of the implanted samples exhibited normal cellular growth and morphology. X-ray photoelectron spectroscopy and water contact angle analysis showed that COOH+ ion implantation rearranges chemical bonds and produces some new polar O-containing groups on the surface. The formation of polar functional groups, together with increase of roughness, induced an increase in hydrophilicity, which in turn improved the surface hemocompatibility of polypropylene. Carboxyl ion (COOH +) implantation was performed at 50 keV with different fluences for polypropylene. Hemocompatibility tests show that blood coagulation time and recalcification time of polypropylene were enhanced significantly with the increased fluence. At the same time, the human endothelial cells grown on the surface of the implanted samples demonstrate normal cellular growth and morphology. X-ray photoelectron spectroscopy and water contact angle analysis showed that COOH + ion implantation rearranges chemical bonds and produces some new polar O-containing groups on the surface. The formation of polar functional groups, together with increase of roughness, induced an increase in hydrophilicity, which in turn improved the surface hemocompatibility of polypropylene.