The left atrial appendage is the remnant of the left atrium of the original embryo and the passage of the pulmonary venous blood into the left ventricle. It is composed of the rich comb muscle and the muscle trabecula. The appearance shows a blind end structure with narrow and wide entrance. It is a good location of the thrombus and an important source of the embolus of the apoplexy of the heart. Echocardiography uses the advantages of various new techniques (CDFI, TDI, STI, VFM, VVI, CS, 3D-ECH) to evaluate the changes of left atrial appendage, structure and hemodynamics, which can predict and evaluate the risk of thromboembolism in the early stage.