Objective To prepare a thrombus-targeted ultrasonic contrast agent and to investigate its targeted ability to fresh blood clots. Methods We first synthesized FITC-KGDS-Palm compound, and then prepared thrombus-targeted microbubbles using "ultrasound & high speed shearing method".Fluorescence labeling thrombus-specific peptides and KGDS,directed at the activated glycoprotein(GP)Ⅱb/Ⅲa receptor of platelets were attached to the surface of lipid microbubbles. The concentration and size of TUCA were measured by Malvern Zeta Sizer Nano-ZS590 and Coulter counter.Immunofluorescence was applied to confirm the conjugation.The conjunct ratio was assessed by flow cytometer (FCM).Results The KGDS-TUCA was straw yellow turbid liquor,and the concentration was 1.5×10~9/mL,and the average size was 1.5 μm. The targeted microbubbles conjugated with the thrombus-specific peptides showed bright green rings by fluorescence microscope.FCM demonstrated that the wavelength of shell of KGDS-TUCA changed greatly,and the conjunct ratio was 90.04%.In vitro study showed KGDS-TUCA remained stable for 48 h at 4 ℃ and target-attached to blood clots and showed good stability.Conclusion The ultrasound & high speed shearing method to prepare TUCA is easy and in favor of purification.KGDS-TUCA has high specific biological activity.The conjunct ratio and stability of KGDS-TUCA are excellent.