Abstract: Mitral regurgitation is a common valve disease, among which functional mitral regurgitation (FMR) is more common. Echocardiography is still the preferred imaging method in the evaluation of mitral valve disease, and plays an important role in the diagnosis, monitoring and treatment of patients with functional mitral regurgitation. Real time three dimensional transesophageal echocardiography (RT3DE) can not only be used for real-time dynamic intraoperative monitoring, but also for offline detailed evaluation of FMR annular lobe parameters in combination with relevant quantitative software, which is helpful to understand the mechanism of FMR lesions and their dynamic changes, and can also provide preoperative guidance for mitral valve repair. This article reviews the research progress of real-time three-dimensional echocardiography in functional mitral regurgitation disease.