The main role of echocardiography in the diagnosis of pulmonary hypertension is to directly estimate pulmonary artery pressure and to assist in the etiologic diagnosis of pulmonary hypertension. In the absence of combined pulmonary stenosis and right ventricular outflow tract obstruction, the systolic pressure of the pulmonary artery is equal to the right ventricular systolic pressure, and the systolic pressure of the pulmonary artery can be estimated directly by measuring the regurgitant pressure difference of the tricuspid valve according to spectral Doppler. If the regurgitant pressure difference of tricuspid valve is >35 mmHg on echocardiography, mild pulmonary hypertension can be considered; if the regurgitant pressure difference is <35 mmHg, basically pulmonary hypertension is not considered; if the regurgitant pressure difference is between 35-54 mmHg, moderate pulmonary hypertension can be considered; if the regurgitant pressure difference is >54 mmHg, severe pulmonary hypertension can be considered. Right heart catheterization is the gold standard for confirming the diagnosis of pulmonary hypertension, but the operation is complicated and risky, and it is not suitable for early diagnostic screening. In contrast, echocardiography is easy to perform and noninvasive, and can both estimate pulmonary artery pressure and screen for the cause of pulmonary hypertension, as well as assess the patient’s condition, treatment, and prognosis.