The mechanism of cardiac function changes caused by rheumatic heart disease is still unclear, and it is currently believed to be related to valvular involvement, myocardial injury, epicardial inflammation and other factors. 1. Valve involvement: rheumatic heart disease is a kind of allergic disease related to group A β-hemolytic streptococcal infection, and the M protein in group A streptococcal bacteria and human heart valves have cross-antigenicity, which can cause cross-immune reaction. Among them, the mitral valve is most often involved, and the lesion of the valve will lead to the reduction of the contractile function of the left ventricle, which will cause the change of cardiac function. 2. Myocardial injury: lesions involving myocardial tissue, commonly found in the left ventricle, interventricular septum, left atrium and left auricle, called rheumatic myocarditis. When the conduction system is involved, conduction block can occur, causing changes in cardiac function. 3. Epicardial inflammation: the lesion involves the dirty layer of the epicardium, which is plasma or fibrinous inflammation. If the exuded fibrin can not be absorbed, it will be mechanized and form constrictive epicarditis, which affects myocardial contraction and causes changes in cardiac function. Diagnosed with rheumatic heart disease, we should seek medical treatment in a timely manner to avoid delay, and follow the doctor’s instructions for standardized treatment.