Abstract: Objective: To investigate the relationship between the left atrium remodeling， von Willebrand factor(vWF) ，D-dimer(DD) ，platelet membrane glycoprotein Ⅱb /Ⅲa(GP Ⅱb /Ⅲa) and left atrial thrombosis， and to explore the mechanisms of thrombosis.Methods: One hundred cases were divided into atrial fibrillation group(60 cases) ， sinus rhythm group(20 cases) and normal control group(20 cases) .Fourty-one cases of atrial fibrillation group were subdivided into thrombosis positive group(21 cases) and thrombosis negative group (20 cases) according to the results of esophageal echocardiography.All cases were detected by transthoraial and transesophageal echocardiography(TTE) .The data of left atrial diameter(LA-D) and thrombosis of left atrium/left atrial appendage were observed.The levels of DD and vWF and GP Ⅱb /Ⅲa were measured using an enzyme linked immunosorbent assay(ELISA) and flow cytometry.Results: The levels of LA-D，vWF，D-D and GP Ⅱb /Ⅲa of sinus rhythm group， thrombosis negative group and thrombosis positive group were increased(P0.01) .The levels of LA-D、vWF、D-D and GP Ⅱb /Ⅲa of the atrial fibrillation group were significantly higher than that of sinus rhythm and normal control group(P0.01) ，while for the later two groups no significant difference(P0.05) .Conclusions: The atrium remodeling，endothelium damage，platelet activation and thrombin increasing may participate in the thrombosis of left atrium.