Pericardial effusion is usually caused by the accumulation of fluid in the pericardial cavity due to infections, autoimmune diseases, tumors and other factors, which may result in acute pericardial tamponade, heart failure, etc., and even life-threatening. Pericardial effusion can generally be categorized into two types: infectious pericardial effusion and non-infectious pericardial effusion. Infectious pericardial effusion is usually caused by a variety of infections such as bacteria and viruses. Among non-infectious pericardial effusions, autoimmune factors are more common, including systemic autoimmune and autoinflammatory diseases; metastatic tumors are most common among tumor factors; and metabolic diseases. Pericardial effusion may cause patients to experience symptoms such as chest tightness and shortness of breath. When pericardial effusion grows suddenly and dramatically, the pericardium is unable to stretch to accommodate the change in its volume, and the pressure in the pericardial cavity rises sharply, causing pressure on the heart, which may result in symptoms such as dyspnea, dysphagia, and may even be life-threatening. Once a pericardial effusion is diagnosed, aggressive medical treatment should be sought to avoid serious consequences.