Abstract: Aim To investigate antithrombogenecity of low density polyethylene(LDPE) thin films treated by sulfur anhydride plasma. Methods LDPE thin films were treated by sulfur anhydride plasma. The relation of sulfonic group with surface soakage or hydrophilicity and surface free energy were studied by contact angle measurements. Surface composition was characterized with XPS and ATR FTIR spectroscopy. Antithrombogenecity of the surface was analyzed with blood coagulation measurements in vitro. Results Sulfonic group can covalently bind with the LDPE surface molecule by using the technique of sulfur anhydride plasma treatment and the molecular composition of the surface with antithrombogenecity was obtained. Conclusion LDPE thin films surface treated by sulfur anhydride plasma have a good antithrombogenecity.