Abstract: Objective To diagnose and analyze the isolated anterior mitral cleft by routine transthoracic echocardiography, and to evaluate the clinical value of routine transthoracic echocardiography in the diagnosis of the isolated anterior mitral cleft. Methods Total 108 patients with isolated anterior mitral cleft were found by transthoracic echocardiography in Tongji Hospital Affiliated to Tongji Medical College of Huazhong University of Science and Technology and the First Hospital Affiliated to China University of Science and Technology from March 2015 to May 2020. Through parasternal left long axis section, mitral valve horizontal left ventricular short axis section, apical four-chamber section, apical two-chamber section and apical three-chamber section, the morphological characteristics, echo and location, length, width of the mitral by 2 D echocardiography, and the origin of the reflux beam and the degree of reflux by color Doppler flow imaging. The diameter of left atrium, left ventricular and left ventricular ejection fraction were measured. According to the recommendation of American Society of Echocardiography, the anterior mitral cleft were located by the mitral valve nomography proposed by Carpentier et al, and compared with the intraoperative findings. Results The echo of the mitral valve anterior lobe was interrupted and showed a "fissure" shape by 2 D echocardiography, and the reflux beam was originated from the cleft by color Doppler, which was the characteristic manifestation of the anterior mitral cleft. Of the 108 patients with the isolated anterior mitral cleft, 87 were in zone A3, 6 in zone A2, 9 in zone A1 and 6 in two or more zones; 12 with severe mitral regurgitation(MR), 9 with moderate-severe MR, 12 with moderate MR, 60 with mild-moderate MR, 15 with mild MR; 27 with mitral valve prolapse. Of the 75 patients who had previously undergone echocardiography, only a very small number were suspected the isolated anterior mitral cleft. Of the 24 patients who underwent surgery, 22 underwent valvular repair or valvuloplasty, and 2 underwent valve replacement due to serious reflux. Among the 24 patients, 17 had complete valvular fissure and 7 had partial valvular fissure. All the 24 patients who had undergone surgery were diagnosed accurately. Conclusion The incidence of the isolated anterior mitral cleft is higher, and transthoracic echocardiography can accurately diagnose the isolated anterior mitral cleft and its complications, which has important clinical value in selecting treatment plan or follow-up.