When 2 or more valves are involved by the same etiology, most commonly mitral valve combined with aortic valve lesions, it is called combined valve disease. One valve lesion can affect or involve the other valve as the disease progresses, resulting in relative stenosis or incomplete closure. For example, rheumatic mitral stenosis can cause pulmonary hypertension, resulting in increased pressure load on the right ventricle, causing hypertrophy and dilatation of the right ventricle and resulting in tricuspid valve insufficiency. The impact of combined valve lesions on cardiac function is comprehensive, and their prognosis is worse than that of individual valve lesions. Before surgery, each valve must be examined in detail to clarify the diagnosis to avoid omissions in intraoperative management, resulting in poor surgical outcomes. Preoperative examination should be carefully performed to analyze the lesions comprehensively and, if necessary, repeatedly perform echocardiography or cardiac catheterization to confirm the site, degree, and extent of lesions and cardiac function.