Pulmonary arterial hypertension（PAH）is a chronic progressive disease characterized by reduced exercise tolerance and right heart dysfunction，which can eventually lead to right heart failure. Cardiopulmonary exercise test（CPET）is a non - invasive assessment tool that comprehensively evaluates circulatory，respiratory，metabolic，and muscular functions under resting and exercise conditions. This article reviews the application and research progress of CEPT in PAH.