Coronary microvascular dysfunction (CMD), as an urgent clinical challenge after percutaneous coronary intervention for ST-segment elevation myocardial infarction (STEMI), has become a research hotspot in the cardiovascular field for its pathophysiological mechanisms and early accurate assessment strategies. The paper systematically summarizes the molecular mechanisms of CMD after reperfusion therapy in STEMI patients, and at the level of diagnostic technology, it deeply analyzes the clinical application value of invasive assessment tools such as coronary flow reserve fraction and index of microcirculatory resistance, and focuses on the unique advantages of quantitative cardiac magnetic resonance analysis for visual assessment of microcirculatory function, aiming to construct a multidimensional assessment system for CMD after STEMI, which will provide a theoretical basis for optimizing the risk stratification of cardiovascular events and formulating individualized treatment strategies.